| Sign In to gain access to subscriptions and/or personal tools. |
An Immunohistochemical Approach to Differentiate Hepatic Lipidosis from Hepatic Phospholipidosis in RatsPfizer Global Research & Development, Ann Arbor, Michigan 48105 Correspondence: Address correspondence to Leslie A. Obert, Pfizer Global Research and Development, 2800 Plymouth Road, Ann Arbor, Michigan 48105; e-mail:leslie.obert{at}pfizer.com
Hepatocellular vacuolation can be a diagnostic challenge since cytoplasmic accumulations of various substances (lipid, water, phospholipids, glycogen, and plasma) can have a similar morphology. Cytoplasmic accumulation of phospholipids following administration of cationic amphiphilic drugs (CAD) can be particularly difficult to differentiate from nonphosphorylated lipid accumulations at the light microscopic level. Histochemical methods (Sudan Black, Oil Red-O, Nile Blue, etc.) can be used to identify both nonphosphorylated and/or phosphorylated lipid accumulations, but these techniques require non-paraffin-embedded tissue and are only moderately sensitive. Thus, electron microscopy is often utilized to achieve a definitive diagnosis based upon the characteristic morphologic features of phospholipid accumulations; however, this is a low throughput and labor intense procedure. In this report, we describe the use of immunohistochemical staining for LAMP-2 (a lysosome-associated protein) and adipophilin (a protein that forms the membrane around non-lysosomal lipid droplets) to differentiate phospholipidosis and lipidosis, respectively in the livers of rats. This staining procedure can be performed on formalin-fixed paraffin embedded tissues, is more sensitive than histochemistry, and easier to perform than ultrastructural evaluation.
Key Words: LAMP • adipophilin • liver • rat • vacuolation • phospholipidosis • lipidosis • immunohistochemistry Abbreviations: CAD, Cationic Amphiphilic Drug • LAMP, Lysosome-associated membrane protein • IHC, Immunohistochemistry • ADRP, Adipose-differentiation-related protein
Cytoplasmic accumulation of phospholipids following administration of cationic amphiphilic drugs (CAD) can be particularly difficult to differentiate from nonphosphorylated lipid accumulations at the light microscopic level even though their subcellular/organelle locations, mechanisms of formation, and ultrastructural morphology are quite different. It has been well established that lysosomes play an integral role in the etiology of CAD-induced phospholipidosis (Reasor, 1984; Kodavanti, 1990). Subcellular localization studies demonstrated that lysosomes are the primary site for phospholipid accumulation (Matsuzawa, 1980; Kacew, 1987). Electron microscopy is usually required to elucidate the morphologic features associated with the storage of this material (Kacew, 1997). The common feature to all forms of this alteration is distention of membrane-bound cytoplasmic vacuoles. These intravesicular, single-membrane, electron-dense, concentric configurations contain primarily stored phospholipids, which results from an inability of the cell to catabolize this substrate (Hostetler, 1984). The most common ultrastructural manifestations are concentric lamellar bodies. These lamellae arise from the homogenous lysosomal matrix that undergoes further transformation into amorphous granular or membranous material (Reasor, 1981). The presence of clear cytoplasmic vacuoles is another morphologic manifestation of CAD storage. These distended membrane-bound vesicles contain predominantly electron-lucent material consistent with phospholipid as determined by acid hematein histochemical staining (Benitz 1968; Thelmo, 1978; Frisch, 1979; Ruben, 1989). To identify phospholipid and nonphosphorylated lipid histochemically, non-paraffin-embedded tissue samples are required, which are often not available. Thus, an alternative method to differentiate nonphosphorylated lipid accumulations from phospholipid or other lysosomal accumulations, which uses formalin-fixed, paraffin-embedded tissue samples would be useful. One approach is to immunohistochemically label the membrane proteins most commonly associated with these different lipid accumulations: LAMP-2 protein for phospholipid and adipophilin protein for nonphosphorylated lipids. The lysosome-associated membrane protein LAMP-2 and structurally similar but genomically distinct (located on a different gene with only 37% sequence homology) LAMP-1 are type 1 glycoproteins localized primarily on the outer membrane of the lysosome and are recognized as major constituents of the lysosomal membrane (Chen, 1988; Fambrough, 1988; Howe, 1988; Viitala, 1988; Cha, 1990; Fukuda, 1991; Peters, 1994; Konecki, 1995; Cuervo, 2000). Roles for LAMP-2 in cell-cell or cell-extracellular matrix adhesion and in maturation of autophagic vacuoles have also been proposed (Lippincott-Schwartz, 1987; Carlsson, 1988; Licheter-Konecki, 1999; Saitoh, 1992; Tanaka, 2000). LAMP proteins can also be detected in lower amounts in endosomes and in the plasma membrane (Furuno and Himeno, 1989; Akasaki, 1993; Furuta, 1999). The lamp2 gene undergoes alternative splicing resulting in different isoforms with different tissue distribution (Gough, 1995; Hatem, 1995; Konecki, 1995). In humans, hLAMP-2B predominates in brain and muscle, and hLAMP-2A is the predominant form in placenta, lung, liver, kidney, pancreas, and prostate gland. LAMP-1 is an integral membrane protein that is transported from the trans-Golgi network to endosomes and then lysosomes. Upon cell activation, LAMP-1 is transferred to the plasma membrane and promotes adhesion of human peripheral blood mononuclear cells to vascular endothelium (Himeno, 1989; Arterburn, 1990; Zot 1990). In contrast, LAMP-2 is ubiquitously distributed and evolutionarily conserved. It is involved in the direct uptake of cytosolic proteins in lysosomes and also participates in the endocytic pathway (Lippincott-Schwartz, 1987; Carlsson, 1988; Saitoh 1992; Cuervo, 1996; Licheter-Konecki, 1999; Tanaka 2000). Originally, the term adipose-differentiation-related protein (ADRP) was coined to reflect this protein’s early appearance during adipocyte differentiation and its apparent specific expression in adipocytes (Jiang, 1992; Eisinger, 1993). However, this protein was renamed adipophilin to emphasize that it is a more general lipid-binding adipose-loving protein (Heid, 1998). Adipophilin functions, together with intermediate filaments, in the packaging, transport and deposition of cytosolic lipid droplets (Heid 1996, 1998; Gao, 1999, 2000). Adipophilin has been strongly conserved during evolution as evidenced by its high sequence homology and immunological cross-reactivity over a range of species (human, bovine, pig, dog, rat, and mouse; Heid, 1998). Heid et al. (1998) demonstrated that adipophilin occurs in a wide range of cells including fibroblasts, endothelial cells, and epithelial cells at the surface of lipid droplets. Adipophilin not only encircles droplets mainly composed of triglycerides, but also droplets rich in cholesterol stored as steroid hormone precursors in adrenocortical cells (Weiss, 1988). Expression of adipophilin in tissues is restricted to certain cell types, such as lactating mammary epithelial cells, adrenal cortex cells, testicular Sertoli and Leydig cells, and steatotic hepatocytes in alcoholic liver cirrhosis (Heid, 1998). Heid et al. proposed adipophilin as a new marker for the identification of specialized differentiated cells containing lipid droplets and for diseases associated with fat-accumulating cells. Lee et al. (1994) suggested one potential diagnostic use for adipophilin is to assess early or minor fatty change in liver biopsies, since microvesicular fat inclusions in hepatocytes may be difficult to distinguish morphologically from glycogen accumulation or certain degenerative cellular changes (Bannasch 1968; Lee, 1994). In addition, conventional fat-staining histochemical methods such as Sudan Black and Oil Red-O staining require non-paraffin-embedded tissue and are only moderately sensitive (Lee, 1994). However, glycogen accumulation in the rat liver can be identified using the Periodic acid-Schiff (PAS) reaction (Corrin, 1968). Taking advantage of the membrane-bound nature of phospholipid and lipid cytoplasmic accumulations is an approach investigated in this study. Thus, immunohistochemical staining for LAMP-2 and adipophilin proteins were evaluated in liver tissue from non-fasted control rats (glycogen accumulation; Corrin, 1968), fasted control rats (hepatic lipidosis; Delzenne, 1997), and rats treated with a CAD (hepatic phospholipidosis) to determine if they can be used to distinguish the different lipid-containing vacuoles.
Animals and Tissues Female Sprague–Dawley (Crl:CD(SD)IGS BR) rats, which were approximately 6–8 weeks old and weighed 125–225 grams at study initiation, were obtained from Charles River Laboratories. All in-life animal procedures were conducted under an IACUC approved protocol and in an AAALC accredited facility. Standard procedures/conditions for animal care, feeding, and maintenance of room, caging, and environment were applied. For the hepatic lipidosis study, animals were fasted for 18 hours, euthanized by CO2 and exanguinated via cardiac puncture. Nonfasted animals served as controls. Tissues were fixed in 10% buffered formalin, embedded in paraffin, sectioned at 3 microns, and stained with hematoxylin and eosin for histologic evaluation. For the hepatic phospholipidosis samples, archival paraffin-embedded tissue blocks were utilized from a 7-day dose-range finding study of an experimental compound that had cationic amphiphilic properties and caused disseminated phospholipidosis in dosed-rats as observed by light microscopic examination and confirmed via electron microscopy.
Immunohistochemistry (IHC)
Electron Microscopy
Microscopic Evaluation of Live The hepatocyte cytoplasm was expanded by irregular non-membrane bound clear spaces (lacy), which was characteristic of normal glycogen storage in a nonfasted state. Non-fasted rats also had rare lipid vacuoles evident within hepatocytes (Figure 1A). Rats fasted for 18 hours exhibited mild lipid accumulation within hepatocytes, which was characterized by one to multiple variably sized, discrete, round, membrane-bound clear vacuoles within the cytoplasm. In addition, these rats had a depletion of their hepatocyte glycogen stores as evidenced by the loss of the lacy staining pattern observed in the nonfasted rats (Figure 1B). CAD-treated rats had diffuse, moderate to marked vacuolation of hepatocytes that were characterized by multiple irregular to round membrane-bound vacuoles within the cytoplasm (Figure 1C). In addition, multifocal aggregates of foamy macrophages were present within the sinusoidal space of the centrilobular regions. Electron microscopic evaluation of these liver tissues revealed the presence of multiple membrane-bound, variably sized laminated structures consist with phospholipid accumulations, which corresponded to the intracytoplasmic hepatocellular vacuoles observed via light microscopy (Figures 2A and 2B).
Lamp-2 IHC Livers from non-fasted and fasted control rats contained punctate cytoplasmic staining within hepatocytes which was distributed in a linear fashion emanating from the edge of the nuclear membrane. Kupffer cells also contained punctate cytoplasmic staining which was less prominent (Figures 3C, 4A and 3E). Hepatocytes from rats treated with a CAD had intense immunostaining of the lysosomal membranes surrounding the cytoplasmic phospholipid accumulations (vacuoles) and a lighter diffuse staining of the intervening cytoplasm (Figures 3G and 4B).
Adipophilin IHC Livers from fasted control rats were characterized by prominent immunostaining of the membranes surrounding the cytoplasmic lipid vacuoles within hepatocytes, which were located primarily along the cell periphery; whereas, only rare lipid vacuoles stained within hepatocytes from nonfasted control rats. In addition, Ito cells exhibited intense membrane staining of their lipid storage vacuoles (Figures 3B and 3F). The lysosomal membranes surrounding the phospholipid accumulations (vacuoles) within the hepatocytes from rats treated with a CAD did not stain nor did the phospholipid accumulations. Since the CAD-treated rats underwent an overnight fast prior to termination, their hepatocytes contained rare cytoplasmic lipid vacuoles that stained. In addition, lipid storage vacuoles within Ito cells also stained (Figure 3H).
Taking advantage of the membrane-bound nature of phospholipid and lipid cytoplasmic accumulations, immunohistochemistry for LAMP-2 and adipophilin proteins, respectively, was employed to differentiate these sources of hepatocellular vacuolation. Livers from nonfasted (glycogen accumulation) and fasted (lipid accumulation) control rats contained punctate cytoplasmic LAMP-2 immunostaining within hepatocytes; whereas, hepatocytes from rats treated with a CAD exhibited intense immunostaining of the lysosomal membranes surrounding the cytoplasmic phospholipid accumulations. The lysosomal membranes surrounding these phospholipid accumulations did not label immunohistochemically for adipophilin. As expected, the hepatocytes from fasted control rats had prominent adipophilin immunostaining of the membranes surrounding the cytoplasmic lipid vacuoles. We have demonstrated that immunohistochemistry can be used to differentiate cytoplasmic vacuolation due to phospholipidosis and/or other intralysosomal accumulations from lipidosis in the rat liver utilizing antibodies against LAMP-2 and adipophilin, respectively. We believe these staining methods offer considerable advantages over current methods: (1) they can be performed on formalin-fixed, paraffin-embedded tissues, (2) they are more sensitive than histochemistry and (3) they are easier to perform than ultrastructural evaluation. These immunostains also are quite robust and cross-react with several different species. Additionally, LAMP immunostaining can be exploited to delineate the lysosomal membranes surrounding phospholipid accumulations within other cell types. We stained the lysosomal membranes surrounding phospholipid accumulations within renal proximal convoluted tubules and tissue macrophages from the same CAD-treated rats using LAMP-2 and LAMP-1 immunohistochemistry, respectively (data not shown). Likewise, adipophilin immunohistochemistry has been used in our laboratory to label lipid storage vacuoles in multiple tissues including adrenal gland, heart, skin (including sebaceous glands), mammary gland, and adipose tissue (data not shown).
Akasaki, K, Fukuzawa, H, Kinoshita, H, Furuno, K, & Tsuji, H. (1993). Cycling of two endogenous lysosomal membrane proteins, lamp-2 and acid phosphatase, between the cell surface and lysosomes in cultured rat hepatocytes. J Biochem, 114, 598-604 Arterburn, LM, Earles, BJ, & August, JT. (1990). The disulfide structure of mouse lysosome-associated membrane protein. J Biol Chem, 265, 7419-23 Bannasch, P. (1968). The cytoplasm of hepatocytes during carcinogenesis. Recent Results Cancer Res, 19, 1-105 Benitz, KF, & Kramer, AW. (1968). Piperamide-induced morphological changes in the choroid plexus. Fd Cosmetics Toxicol, 6, 125-133[CrossRef] Carlsson, SR, Roth, J, Piller, F, & Fukuda, M. (1988). Isolation and characterization of human lysosomal membrane glycoproteins, h-lamp-1 and h-lamp-2. Major sialoglycoproteins carrying polylactosaminoglycan. J Biol Chem, 263, 18911-9 Cha, Y, Holland, SM, & August, JT. (1990). The cDNA sequence of mouse LAMP-2. Evidence for two classes of lysosomal membrane glycoproteins. J Biol Chem, 265, 5008-13 Chen, JW, Cha, Y, Yuksel, KU, Gracy, RW, & August, JT. (1988). Isolation and sequencing of a cDNA clone encoding lysosomal membrane glycoprotein mouse LAMP-1. Sequence similarity to proteins bearing onco-differentiation antigens. J Biol Chem, 263, 8754-8 Chen, JW, Murphy, TL, Willingham, MC, Pastan, I, & August, JT. (1985). Identification of two lysosomal membrane glycoproteins. J Cell Biol, 101, 85-95 Chen, JW, Murphy, TL, Willingham, MC, Pastan, I, & August, JT. (1986). Lysosomal membrane glycoproteins: properties of LAMP-1 and LAMP-2. Biochem Soc Symp, 51, 97-112[Medline] [Order article via Infotrieve] Corrin, B, & Aterman, K. (1968). The pattern of glycogen distribution in the liver. Amer J Anat, 122, 57-72[CrossRef] Cuervo, AM, & Dice, JF. (1996). A receptor for the selective uptake and degradation of proteins by lysosomes. Science, 273, 501-3[Abstract] Cuervo, AM, & Dice, JF. (2000). Unique properties of lamp2a compared to other lamp2 isoforms. J Cell Sci, 113, 4441-50[Abstract] Delzenne, NM, Hernaux, NA, & Taper, HS. (1997). A new model of acute liver steatosis induced in rats by fasting followed by refeeding a high carbohydrate-fat free diet. Biochemical and morphological analysis. J Hepatol, 26, 880-5[CrossRef][Web of Science][Medline] [Order article via Infotrieve] Eisinger, DP, & Serrero, G. (1993). Structure of the gene encoding mouse adipose differentiation-related protein. Genomics, 16, 638-44[CrossRef][Web of Science][Medline] [Order article via Infotrieve] Fambrough, DM, Takeyasu, K, Lippincott-Schwarz, J, & Siegel, NR. (1988). Structure of LEP100, a glycoprotein that shuttles between lysosomes and the plasma membrane, deduced from the nucleotide sequence of the encoding cDNA. J Cell Biol, 106, 61-7 Frisch, W, & Lüllmann-Rauch, R. (1979). Differential effects of chloroquine and of several other amphiphilic cationic drugs upon rat choroid plexus. Acta Neuropathol, 46, 203-8[CrossRef][Medline] [Order article via Infotrieve] Fukuda, M. (1991). Lysosomal membrane glycoproteins. Structure, biosynthesis, and intracellular trafficking. J Biol Chem, 266, 21327-30 Fukuda, M, Viitala, J, Matteson, J, & Carlsson, SR. (1988). Cloning of cDNAs encoding human lysosomal membrane glycoproteins, h-lamp-1 and h-lamp-2. Comparison of their deduced amino acid sequences. J Biol Chem, 263, 18920-8 Furuno, K, Yano, S, Akasaki, K, Tanaka, Y, Yamaguchi, Y, Tsuji, H, Himeno, M, & Kato, K. (1989). Biochemical analysis of the movement of a major lysosomal membrane glycoprotein in the endocytic membrane system. J Biochem, 106, 717-22 Furuta, K, Yang, X-L, Chen, J-S, Hamilton, SR, & August, JT. (1999). Differential expression of the lysosome-associated membrane proteins in normal human tissues. Arch Biochem Biophys, 365, 75-82[CrossRef][Web of Science][Medline] [Order article via Infotrieve] Gao, J, & Serrero, G. (1999). Adipose differentiation related protein (ADRP) expressed in transfected COS-7 cells selectively stimulates long chain fatty acid uptake. J Biol Chem, 274, 16825-30 Gao, J, Ye, H, & Serrero, G. (2000). Stimulation of adipose differentiation related protein (ADRP) expression in adipocyte precursors by long-chain fatty acids. J Cell Physiol, 182, 297-302[CrossRef][Web of Science][Medline] [Order article via Infotrieve] Gough, NR, Hatem, CL, & Fambrough, DM. (1995). The family of LAMP-2 proteins arises by alternative splicing from aa single gene: characterization of the avian LAMP-2 gene and identification of mammalian homologs of LAMP-2b and LAMP-2c. DNA Cell Biol, 14, 863-7[Web of Science][Medline] [Order article via Infotrieve] Hatem, CL, Gough, NR, & Fambrough, DM. (1995). Multiple mRNAs encode the avian lysosomal membrane protein LAMP-2 resulting in alternative transmembrane and cytoplasmic domains. J Cell Sci, 108, 2093-100[Abstract] Heid, HW, Moll, R, Schwetlick, I, Rackwitz, H-R, & Keenan, TW. (1998). Adipophilin is a specific marker of lipid accumulation in diverse cell types and diseases. Cell Tissue Res, 294, 30-21 Heid, HW, Schnölzer, M, & Keenan, TW. (1996). Adipocyte differentiation related protein is secreted into milk as a constituent of milk lipid globule membrane. Biochem J, 320, 1025-30[Web of Science][Medline] [Order article via Infotrieve] Himeno, M, Noguchi, Y, Sasaki, H, Tanaka, Y, Furuno, K, Kono, A, Sakaki, Y, & Kato, K. (1989). Isolation and sequencing of a cDNA clone encoding 107 kDa sialoglycoprotein in rat liver lysosomal membranes. FEBS Lett, 244, 351-356[CrossRef][Web of Science][Medline] [Order article via Infotrieve] Hostetler, KY. (1984). Molecular studies of the induction of cellular phospholipidosis by cationic amphiphilic drugs. Fed Proc, 43, 2582-5[Web of Science][Medline] [Order article via Infotrieve] Howe, CL, Granger, BL, Hull, M, Green, SA, Gabel, CA, Helenius, A, & Mellman, I. (1988). Derived protein sequence, oligosaccharides, and membrane insertion of the 120-kDa lysosomal membrane glycoprotein (lgp120): Identification of a highly conserved family of lysosomal membrane glycoproteins. Proc Natl Acad Sci USA, 85, 7577-81 Hughes, EN, & August, JT. (1981). Characterization of plasma membrane proteins identified by monoclonal antibodies. J Biol Chem, 256, 664-71 Jiang, H-P, & Serrero, G. (1992). Isolation and characterization of a full length cDNA coding for an adipose differentiation-related protein. Proc Natl Acad Sci USA, 89, 7856-60 Kacew, S. (1987). Cationic amphiphilic drug-induced renal cortical lysosomal phospholipidosis: an in vivo comparative study with gentamicin and chlorphentermine. Toxicol Appl Pharmacol, 91, 469-76[CrossRef][Web of Science][Medline] [Order article via Infotrieve] Kacew, S. (1997). Cationic lipophilic drugs: Mechanisms of action, potential consequences, and reversibility. Drug Metabolism Rev, 29, 355-68[Web of Science][Medline] [Order article via Infotrieve] Kodavanti, UP, & Mehendale, HM. (1990). Cationic amphiphilic drugs and phospholipid storage disorder. Pharmacol Rev, 42, 327-54[Web of Science][Medline] [Order article via Infotrieve] Konecki, DS, Foetisch, K, Zimmer, KP, Schlotter, M, & Konecki, UL. (1995). An Alternatively spliced form of the human lysosome-associated membrane protein-2 gene is expressed in a tissue-specific manner. Biochem Biophys Res Commun, 215, 757-67[CrossRef][Web of Science][Medline] [Order article via Infotrieve] Lee, RJ. (1994). Diagnostic Liver Pathology. St. Louis, MO: Mosby Licheter-Konecki, U, Moter, SE, Krawisz, BR, Schlotter, M, Hipke, C, & Konecki, DS. (1999). Expression patterns of murine lysosome-associated membrane protein 2 (Lamp-2) transcripts during morphogenesis. Differentiation, 65, 43-58[CrossRef][Web of Science][Medline] [Order article via Infotrieve] Lippincott-Schwartz, J, & Fambrough, DM. (1987). Cycling of the integral membrane glycoprotein, LEP100, between plasma membrane and lysosomes: kinetic and morphological analysis. Cell, 49, 669-77[CrossRef][Web of Science][Medline] [Order article via Infotrieve] Mane, SM, Marzella, L, Bainton, DF, Holt, VK, Cha, Y, Hildreth, JE, & August, JT. (1989). Purification and characterization of human lysosomal membrane glycoproteins. Arch Biochem Biophys, 268, 360-78[CrossRef][Web of Science][Medline] [Order article via Infotrieve] Matsuzawa, Y, & Hostetler, KY. (1980). Studies on drug-induced lipidosis: subcellular localization of phospholipid and cholesterol in the liver of rats treated with chloroquine or 4,4'-bis(diethylaminoethoxy) Peters, C, & von Figura, K. (1994). Biogenesis of lysosomal membranes. FEBS Lett, 346, 108-14[CrossRef][Web of Science][Medline] [Order article via Infotrieve] Reasor, J, Kacew, S, & Thoma-Laurie, DL. (1984). Toxicology and the Newborn. Amsterdam, Netherlands: Elsevier Reasor, MJ. (1981). Drug-induced lipidosis and the alveolar macrophage. Toxicol Appl Pharmacol, 20, 1-33[CrossRef] Ruben, Z, Dodd, DC, Rorig, KJ, & Anderson, SN. (1989). Disobutamide: a model agent for investigating intracellular drug storage. Toxicol Appl Pharmacol, 97, 57-71[CrossRef][Web of Science][Medline] [Order article via Infotrieve] Saitoh, O, Wang, WC, Lotan, R, & Fukuda, M. (1992). Differential glycosylation and cells surface expression of lysosomal membrane glycoproteins in sublines of a human colon cancer exhibiting distinct metastatic potentials. J Biol Chem, 267, 5700-11 Tanaka, Y, Guhde, G, Suter, A, Eskelinen, E-L, Hartmann, D, Lüllmann-Rauch, R, Janssen, PML, Blanz, J, von Figura, K, & Saftig, P. (2000). Accumulation of autophagic vacuoles and cardiomyopathy in Lamp-2-deficient mice. Nature, 406, 902-6[CrossRef][Medline] [Order article via Infotrieve] Thelmo, WL, & Levine, S. (1978). Renal lesions induced induced by tilorone and an analog. Ultrastructure and acid phosphatase study. Am J Pathol, 91, 355-60[Abstract] Viitala, J, Carlsson, SR, Siebert, PD, & Fukuda, M. (1988). Molecular cloning of cDNAs encoding lamp A, a human lysosomal membrane glycoprotein with apparent mr 120,000. Proc Natl Acad Sci USA, 85, 3743-7 Weiss, L. (1988). Cell and Tissue Biology. Baltimore, Munich: Urban and Schwarzenberg Zot, AS, & Fambrough, DM. (1990). Structure of a gene for a lysosomal membrane glycoprotein (LEP100). Housekeeping gene with unexpected exon organization. J Biol Chem, 265, 20988-95
Toxicologic Pathology, Vol. 35, No. 5,
728-734 (2007)
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
|
|
 |
|
Sign In to gain access to subscriptions and/or personal tools.
Top
Abstract
Introduction
,β-diethyldiphenylethan. J Lipid Res, 21, 202-14