Lodge A P, Howard M R, McNamee C J, Moss D J
Department of Human Anatomy and Cell Biology, The University of Liverpool, New Medical School, Ashton St., L69 3GE, Liverpool, UK.
Brain Res Mol Brain Res. 2000 Oct 20;82(1-2):84-94. doi: 10.1016/s0169-328x(00)00184-4.
The chick glycoprotein GP55 has been shown to inhibit the growth and adhesion of DRG and forebrain neurons. GP55 consists of several members of the IgLON family, a group of glycoproteins including LAMP, OBCAM, CEPU-1 (chick)/neurotrimin (rat) and neurotractin (chick)/kilon (rat) thought to play a role in the guidance of growing axons. IgLONs belong to the Ig superfamily and have three C2 domains and a glycosyl phosphatidylinositol anchor which tethers them to the neuronal plasma membrane. We have now completed the deduced amino acid sequence for two isoforms of chicken OBCAM and used recombinant LAMP, OBCAM and CEPU-1 to raise antisera specific to these three IgLONs. LAMP and CEPU-1 are co-expressed on DRG and sympathetic neurons, while both overlapping and distinct expression patterns for LAMP, OBCAM and CEPU-1 are observed in retina. Analysis of IgLON mRNA expression reveals that alternatively spliced forms of LAMP and CEPU-1 are developmentally regulated. In an attempt to understand how the IgLONs function, we have begun to characterise their molecular interactions. LAMP and CEPU-1 have already been shown to interact homophilically. We now confirm that OBCAM will bind homophilically and also that LAMP, OBCAM and CEPU-1 will interact heterophilically with each other. We propose that IgLON activity will depend on the complement of IgLONs expressed by each neuron.
鸡糖蛋白GP55已被证明可抑制背根神经节（DRG）和前脑神经元的生长与黏附。GP55由免疫球蛋白超家族（IgLON）的几个成员组成，这是一组糖蛋白，包括淋巴细胞抗原8（LAMP）、鸡脑钙黏附分子（OBCAM）、鸡CEPU-1/大鼠神经调节素以及鸡神经束蛋白/大鼠kilon，它们被认为在生长轴突的导向中发挥作用。免疫球蛋白超家族成员属于免疫球蛋白超家族，具有三个C2结构域和一个糖基磷脂酰肌醇锚定物，该锚定物将它们连接到神经元质膜上。我们现已完成鸡OBCAM两种异构体的推导氨基酸序列，并使用重组LAMP、OBCAM和CEPU-1制备针对这三种免疫球蛋白超家族成员的特异性抗血清。LAMP和CEPU-1在背根神经节和交感神经元上共同表达，而在视网膜中观察到LAMP、OBCAM和CEPU-1存在重叠和不同的表达模式。对免疫球蛋白超家族成员mRNA表达的分析表明，LAMP和CEPU-1的可变剪接形式受发育调控。为了了解免疫球蛋白超家族成员的功能，我们已开始对其分子相互作用进行表征。LAMP和CEPU-1已被证明可进行同源性相互作用。我们现在证实OBCAM也将进行同源性结合，并且LAMP、OBCAM和CEPU-1将相互进行异源性结合。我们提出免疫球蛋白超家族成员的活性将取决于每个神经元所表达的免疫球蛋白超家族成员的互补情况。
