Simple Purification and Functional Reconstitution of Octopus Photoreceptor Gq, Which Couples Rhodopsin to Phospholipase C
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- 作者：Satoshi Kikkawa ; Kayo Tominaga ; Masashi Nakagawa ; Tatsuo Iwasa ; and Motoyuki Tsuda
- 刊名：Biochemistry
- 出版年：1996
- 出版时间：December 10, 1996
- 年：1996
- 卷：35
- 期：49
- 页码：15857 - 15864
- 全文大小：420K
- 年卷期：v.35,no.49(December 10, 1996)
- ISSN：1520-4995
文摘
In invertebrate photoreceptors, illuminated rhodopsin activatesmultiple G proteins, which areassumed to initiate multiple phototransduction cascades. In thispaper, we focused on one of thephototransduction cascades, which utilizes rhodopsin, aGq-like G protein, and phospholipase C (PLC).A Gq-like G protein from octopus photoreceptors wassuccessfully purified to apparent homogeneity asan active form by simple two-step chromatography. The purified Gprotein had an 
-trimeric structureconsisting of 44-kDa , 37-kDa , and 9-kDa subunits. The44-kDa subunit was assigned to the Gqclass by western blot with antiserum against mammalianGq and by partial amino acid sequencing ofitsproteolytic fragments. Light-dependent binding of GTPS wasobserved when the purified octopus Gqwas reconstituted with octopus rhodopsin that had been integrated intophospholipid vesicles. OctopusGq activated PLC1 purified from bovine braindose-dependently in the presence of AlF4-.Finally, light-and GTP-dependent activation of PLC1 was observed in areconstitution system consisting of octopusrhodopsin, Gq, and bovine PLC1.
-trimeric structureconsisting of 44-kDa , 37-kDa , and 9-kDa subunits. The44-kDa subunit was assigned to the Gqclass by western blot with antiserum against mammalianGq and by partial amino acid sequencing ofitsproteolytic fragments. Light-dependent binding of GTPS wasobserved when the purified octopus Gqwas reconstituted with octopus rhodopsin that had been integrated intophospholipid vesicles. OctopusGq activated PLC1 purified from bovine braindose-dependently in the presence of AlF4-.Finally, light-and GTP-dependent activation of PLC1 was observed in areconstitution system consisting of octopusrhodopsin, Gq, and bovine PLC1.