标题：β2-Chimaerin is a novel target for diacylglycerol: Binding properties and changes in subcellular localization mediated by ligand binding to its C1 domain
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1999
卷号：96
期号：21
页码：11854-11859
DOI：10.1073/pnas.96.21.11854
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The members of the chimaerin family of Rac-GTPase-activating proteins possess a single C1 domain with high homology to those present in protein kinase C (PKC) isozymes. This domain in PKCs is involved in phorbol ester and diacylglycerol (DAG) binding. We previously have demonstrated that one of the chimaerin isoforms, {beta}2-chimaerin, binds phorbol esters with high affinity. In this study we analyzed the properties of {beta}2-chimaerin as a DAG receptor by using a series of conformationally constrained cyclic DAG analogues (DAG lactones) as probes. We identified analogs that bind to {beta}2-chimaerin with more than 100-fold higher affinity than 1-oleoyl-2-acetylglycerol. The potencies of these analogs approach those of the potent phorbol ester tumor promoters. The different DAG lactones show some selectivity for this novel receptor compared with PKC. Cellular studies revealed that these DAG analogs induce translocation of {beta}2-chimaerin from cytosolic (soluble) to particulate fractions. Using green fluorescent protein-fusion proteins for {beta}2-chimaerin we determined that this novel receptor translocates to the perinuclear region after treatment with DAG lactones. Binding and translocation were prevented by mutation of the conserved Cys-246 in the C1 domain. The structural homology between the C1 domain of {beta}2-chimaerin and the C1b domain of PKC{delta} also was confirmed by modeling analysis. Our results demonstrate that {beta}2-chimaerin is a high affinity receptor for DAG through binding to its C1 domain and supports the emerging concept that multiple pathways transduce signaling through DAG and the phorbol esters.
