t-complex-associated embryonic surface antigen homologous to mLAMP-1. I. Biochemical and molecular analyses.
Previously we described an embryonic cell surface glycoprotein, ESGp, associated with the t-embryonic lethal alleles of the mouse t complex. This antigen is expressed on the cell surface of both early mouse embryos and embryonal carcinoma (EC) cell lines. The antigen is localized to areas of cell-cell contact in EC lines and redistributes to the outer edges of the blastomeres during compaction, thereby indicating a potential role in embryonic cell-cell interaction. We now report that this t-complex-associated ESGp is homologous to the mouse lysosomal-associated membrane protein-1 (LAMP-1). Limited protein sequence analyses of the amino terminal and an internal peptide indicate considerable homology with the LAMP-1 protein. Biochemical parameters such as protein core size, sulfation and phosphorylation status, and resistance to proteolysis also demonstrate homology. While we detect only a single message with a mouse LAMP-1 cDNA probe via Northern blotting, Southern analyses indicate the existence of at least two homologous LAMP-1 genes. Additionally, we present evidence suggesting that ESGp/LAMP-1 serves as a substrate which may be differentially glycosylated by the activities of the gene products of the different t-lethal alleles.
Gray-Bablin
J
J
Department of Biological Sciences, University at Albany, New York 12222, USA.
Acevedo-Schermerhorn
C
C
Gama
R
R
McCormick
P J
PJ
D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000737:chemistry*; D000943:Antigens, Differentiation / Q000737:chemistry*; D018236:Carcinoma, Embryonal / Q000737:chemistry*; D004622:Embryo, Mammalian / Q000737:chemistry*; D005804:Genes, Lethal; D006031:Glycosylation; D051907:Lysosomal Membrane Proteins; D008297:Male; D008562:Membrane Glycoproteins / Q000737:chemistry*; D051379:Mice; D008969:Molecular Sequence Data; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D013737:Testis / Q000737:chemistry; D052118:Lysosomal-Associated Membrane Protein 1
D015703:Antigens, CD; D000943:Antigens, Differentiation; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins; C052255:Lamp1 protein, mouse; D052118:Lysosomal-Associated Membrane Protein 1