Gray-Bablin J, Acevedo-Schermerhorn C, Gama R, McCormick P J
Department of Biological Sciences, University at Albany, New York 12222, USA.
Exp Cell Res. 1997 Nov 1;236(2):501-9. doi: 10.1006/excr.1997.3751.
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.
此前我们描述了一种胚胎细胞表面糖蛋白，即ESGp，它与小鼠t复合体的t-胚胎致死等位基因相关。这种抗原在早期小鼠胚胎和胚胎癌细胞（EC）系的细胞表面均有表达。该抗原定位于EC系中细胞间接触的区域，并在致密化过程中重新分布到卵裂球的外边缘，从而表明其在胚胎细胞间相互作用中可能发挥作用。我们现在报告，这种与t复合体相关的ESGp与小鼠溶酶体相关膜蛋白-1（LAMP-1）同源。对氨基末端和一个内部肽段的有限蛋白质序列分析表明，它与LAMP-1蛋白有相当程度的同源性。蛋白质核心大小、硫酸化和磷酸化状态以及对蛋白水解的抗性等生化参数也显示出同源性。虽然通过Northern印迹法我们用小鼠LAMP-1 cDNA探针仅检测到一条信息，但Southern分析表明至少存在两个同源的LAMP-1基因。此外，我们提供的证据表明，ESGp/LAMP-1作为一种底物，可能被不同t-致死等位基因的基因产物的活性进行差异糖基化。
