Suzuki K, Yanagisawa K
Institute of Biological Sciences, University of Tsukuba, Ibaraki, Japan.
Cell Differ Dev. 1990 Apr;30(1):35-42. doi: 10.1016/0922-3371(90)90072-5.
Macrocyst formation in Dictyostelium discoideum is initiated by the fusion of cells between two opposite mating-type strains, such as NC-4 and HM1. When these cells become fusion-competent under appropriate environmental conditions, a specific protein involved in sexual cell fusion, 138 kDa, appears on the cell surface of both NC-4 and HM1 strains, as reported previously. The present study was carried out to purify and characterize this protein. The 138 kDa protein was shown to be a glycoprotein (gp138) which binds specifically to lectins, WGA, Con-A or LCA, but not to PNA, PHAE4, RCA60 or RCA120. The isoelectric point of the gp138 was determined as pH 4.5-4.9. To confirm again the previous results, a Coomassie blue-stained gel containing the 138-kDa band was cut out following the SDS-polyacrylamide gel electrophoresis, and antiserum against this band protein(s) was obtained. Fab fragments of this antiserum caused the complete inhibition of sexual fusion between NC-4 and HM1 cells.
盘基网柄菌中的大囊泡形成是由两个相对交配型菌株（如NC-4和HM1）之间的细胞融合引发的。如先前报道，当这些细胞在适当的环境条件下具备融合能力时，一种参与性细胞融合的特定蛋白质，即138 kDa蛋白，会出现在NC-4和HM1菌株的细胞表面。本研究旨在纯化和表征这种蛋白质。结果表明，138 kDa蛋白是一种糖蛋白（gp138），它能特异性结合凝集素WGA、Con-A或LCA，但不结合PNA、PHAE4、RCA60或RCA120。gp138的等电点测定为pH 4.5 - 4.9。为再次证实先前的结果，在SDS-聚丙烯酰胺凝胶电泳后，切下含有138 kDa条带的考马斯亮蓝染色凝胶，并获得针对该条带蛋白的抗血清。该抗血清的Fab片段完全抑制了NC-4和HM1细胞之间的性融合。
