Taira E, Nagino T, Tsukamoto Y, Okumura S, Muraoka O, Sakuma F, Miki N
Department of Pharmacology, Osaka University School of Medicine, 2-2 Yamada-oka, Suita, Osaka, 565-0871, Japan.
Exp Cell Res. 1999 Dec 15;253(2):697-703. doi: 10.1006/excr.1999.4713.
Gicerin is a cell adhesion molecule in the immunoglobulin (Ig) superfamily and is expressed abundantly during development in the nervous system. It has homophilic cell adhesion activity and also has heterophilic binding activity with NOF (neurite outgrowth factor) and mediates neurite extension. There are two isoforms of gicerin, one with a short (s-gicerin) and the other with a longer cytoplasmic domain (l-gicerin). We have reported that s-gicerin possesses stronger activities than l-gicerin during cell aggregation, in NOF-binding, and in neurite extension. In this study, we established cell lines which expressed a mutant-gicerin whose cytoplasmic domain was deleted and we compared the above three biological activities of the mutant-gicerin with those of s- and l-gicerin. We found that the mutant-gicerin retained all these activities, but the activities were weaker than those of s-gicerin and almost the same as those of l-gicerin. We concluded that the cytoplasmic domain of gicerin is not essential for optimal adhesive activities of gicerin, but might be involved in the regulation of its activities.
吉塞林是免疫球蛋白（Ig）超家族中的一种细胞粘附分子，在神经系统发育过程中大量表达。它具有同嗜性细胞粘附活性，还与神经突生长因子（NOF）具有异嗜性结合活性，并介导神经突延伸。吉塞林有两种异构体，一种具有短的细胞质结构域（s-吉塞林），另一种具有较长的细胞质结构域（l-吉塞林）。我们已经报道，在细胞聚集、与NOF结合以及神经突延伸过程中，s-吉塞林比l-吉塞林具有更强的活性。在本研究中，我们建立了表达细胞质结构域缺失的突变型吉塞林的细胞系，并将突变型吉塞林的上述三种生物学活性与s-吉塞林和l-吉塞林的活性进行了比较。我们发现突变型吉塞林保留了所有这些活性，但这些活性比s-吉塞林的活性弱，与l-吉塞林的活性几乎相同。我们得出结论，吉塞林的细胞质结构域对于吉塞林的最佳粘附活性不是必需的，但可能参与其活性的调节。
