头足类动物光感受器中的视紫红质、Gq和磷脂酶C激活

Rhodopsin, Gq and phospholipase C activation in cephalopod photoreceptors.

作者信息

Bhatia J, Davies A, Gaudoin J B, Saibil H R

机构信息

Department of Crystallography, Birkbeck College, London, UK.

出版信息

J Photochem Photobiol B. 1996 Aug;35(1-2):19-23. doi: 10.1016/1011-1344(96)07309-5.

DOI:10.1016/1011-1344(96)07309-5

PMID:8823931

Abstract

We present characterization of the rhodopsin, Gq and phosphatidylinositol-specific phospholipase C (PLC) from the signal transduction pathway of cephalopod photoreceptors. Cephalopod rhodopsins are unique in possessing a C-terminal extension of proline-rich repeats, and they have a strong tendency to form ordered arrays. Two-dimensional arrays of a full-length and C-terminally-truncated cephalopod rhodopsin have been obtained. The C termini appear to cluster the rhodopsins into small groups. An AlF4(-)-activated Gq alpha subunit has been isolated and shown to activate a partially purified PLC beta. This 130 kDa PLC, isolated by absorption on heparin agarose, showed a specific activity of 195 nmol of phosphatidylinositol 4,5-bisphosphate hydrolysed per milligram of protein per minute in the presence of 1.6 microM free calcium.

摘要

我们展示了来自头足类动物光感受器信号转导途径的视紫红质、Gq和磷脂酰肌醇特异性磷脂酶C（PLC）的特性。头足类动物视紫红质的独特之处在于其C末端富含脯氨酸的重复序列延伸，并且它们有强烈的形成有序阵列的倾向。已获得全长和C末端截短的头足类动物视紫红质的二维阵列。C末端似乎将视紫红质聚集为小群体。已分离出AlF4(-)激活的Gqα亚基，并证明其可激活部分纯化的PLCβ。通过肝素琼脂糖吸附分离得到的这种130 kDa的PLC，在存在1.6 microM游离钙的情况下，每毫克蛋白质每分钟水解磷脂酰肌醇4,5-二磷酸的比活性为195 nmol。