Taira E, Nagino T, Taniura H, Takaha N, Kim C H, Kuo C H, Li B S, Higuchi H, Miki N
Department of Pharmacology 1, Osaka University Medical School, Japan.
J Biol Chem. 1995 Dec 1;270(48):28681-7. doi: 10.1074/jbc.270.48.28681.
We have cloned a novel cDNA of gicerin, a cell adhesion molecule belonging to the immunoglobulin superfamily. Both gicerin isoforms share the same extracellular domain, which has five immunoglobulin-like loop structures and a transmembrane domain as s-gicerin, but differ in the cytoplasmic tail domain. As the newly identified form has a larger cytoplasmic domain than the previously reported form, we refer to them as l-gicerin and s-gicerin, respectively. l-gicerin is transcribed from a distinct mRNA containing an inserted sequence not found in s-gicerin mRNA which caused a frameshift for the coding region for a cytoplasmic domain. Previous studies demonstrated that gicerin showed a doublet band of 82 and 90 kDa in chicken gizzard smooth muscle. We report that the 82-kDa protein corresponds to s-gicerin and the 90-kDa protein to l-gicerin. We also found that the two gicerin isoforms are expressed differentially in the developing nervous system. Functional analysis of these gicerin isoforms in stable transfectants revealed that they had differ in their homophilic adhesion properties, as well as in heterophilic cell adhesion assayed with neurite outgrowth factor. In addition, these isoforms have neurite-promoting activity by their homophilic adhesion, but differ in their ability to promote neurite outgrowth.
我们克隆了一种新型的gicerin cDNA，gicerin是一种属于免疫球蛋白超家族的细胞粘附分子。两种gicerin亚型共享相同的细胞外结构域，该结构域具有五个免疫球蛋白样环结构和一个跨膜结构域，与s-gicerin相同，但细胞质尾结构域不同。由于新鉴定的形式比先前报道的形式具有更大的细胞质结构域，我们分别将它们称为l-gicerin和s-gicerin。l-gicerin由一种独特的mRNA转录而来，该mRNA含有一个在s-gicerin mRNA中未发现的插入序列，该序列导致细胞质结构域编码区的移码。先前的研究表明，gicerin在鸡胗平滑肌中显示出82 kDa和90 kDa的双峰带。我们报告82 kDa的蛋白对应于s-gicerin，90 kDa的蛋白对应于l-gicerin。我们还发现这两种gicerin亚型在发育中的神经系统中差异表达。对稳定转染子中这些gicerin亚型的功能分析表明，它们在同嗜性粘附特性以及用神经突生长因子测定的异嗜性细胞粘附中存在差异。此外，这些亚型通过其同嗜性粘附具有神经突促进活性，但在促进神经突生长的能力上存在差异。
