T-COMPLEX-ASSOCIATED EMBRYONIC SURFACE-ANTIGEN HOMOLOGOUS TO MLAMP-1 .2. EXPRESSION AND DISTRIBUTION ANALYSES

We have previously demonstrated that a mouse t-complex-associated anti gen (ESGp) is present on the cell surface, specifically at areas of ce ll-cell contact, of cleavage stage embryos and embryonal carcinoma cel l lines. In the accompanying paper, we document isolation, purificatio n, and partial sequencing of this molecule. Amino-terminal and interna l peptide fragments are highly homologous to the mouse lysosomal-assoc iated membrane protein-1 (mLAMP-1). We also demonstrate considerable s imilarity, though not necessarily identity, between these two antigens through both biochemical and molecular analyses. In this report we us e immunological techniques to compare the expression and distribution of these antigens in various cell Lines as well as mouse tissues and p reimplantation stage embryos. The data presented indicate that there a re: (1) different antigenic forms of the ESGp/mLAMP-1 homologues and ( 2) changes in the molecular composition and expression of these forms during embryogenesis and differentiation. It is obvious from these stu dies that mLAMP-1 is not strictly a static molecule whose sole functio n is to protect the lumenal side of the lysosomal membrane but rather is a dynamic molecule of potential import in many other cellular and o rganismal functions. (C) 1997 Academic Press.