The protein phosphatase-1 targeting subunit TIMAP regulates LAMR1 phosphorylation
The protein phosphatase-1 targeting subunit TIMAP regulates LAMR1 phosphorylation
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DOI：
10.1016/j.bbrc.2005.10.089
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发表时间：
2005-12-23
影响因子：
3.1
通讯作者：
Ballermann, BJ
中科院分区：
文献类型：
--
作者：
Kim, K;Li, LJ;Ballermann, BJ
TIMAP是一种异戊烯化的内皮细胞蛋白，其结构域预测其为蛋白磷酸酶-1（PP-1）调节亚基。我们发现，TIMAP与37/67 kDa层粘连蛋白受体（LAMR 1）在酵母双杂交试验中相互作用。在内皮细胞中，内源性TIMAP和LAMR 1共免疫沉淀并共定位于质膜。TIMAP氨基酸261-290，代表TIMAP的第四个锚蛋白重复序列，对于相互作用是必要的和足够的。在缺乏内源性TIMAP的MDCK细胞中，全长TIMAP的过表达，但不是第四锚蛋白结构域中缺失的TIMAP，允许与LAMR 1的免疫共沉淀。PP-1分别与MDCK和内皮细胞中过度表达的和内源性的TIMAP共沉淀。在MDCK细胞中，PP-1与LAMR 1在存在TIMAP的情况下相关，但在不存在TIMAP的情况下不相关。LAMR 1在体外是PP-1的底物，在MDCK细胞中，其磷酸化被全长TIMAP的表达所废除，但不是被第四锚蛋白结构域中的TIMAP缺陷所废除。因此，TIMAP将PP-1靶向至LAMR 1，并且LAMR 1是TIMAP依赖性PP-1底物。(c)2005年爱思唯尔公司All rights reserved.
TIMAP is a prenylated endothelial cell protein with a domain structure that predicts it to be a protein phosphatase-1 (PP-1) regulatory Subunit. We found that TIMAP interacts with the 37/67 kDa laminin receptor (LAMR1) in yeast two-hybrid assays. In endothelial cells, endogenous TIMAP and LAMR1 co-immunoprecipitated and co-localized at the plasma membrane. TIMAP amino acids 261-290, representing the fourth ankyrin repeat of TIMAP, are necessary and sufficient for the interaction. In MDCK cells, lacking endogenous TIMAP, overexpression of full-length TIMAP, but not TIMAP deleted in the fourth ankyrin domain, allowed co-immunoprecipitation with LAMR1. PP-1 co-precipitated with over-expressed and endogenous TIMAP in MDCK and endothelial cells, respectively. In MDCK cells, PP-1 associated with LAMR1 in the presence, but not in the absence, of TIMAP. LAMR1 was a substrate for PP-1 in vitro, and in MDCK cells its phosphorylation was abrogated by expression of full-length TIMAP but not by TIMAP deficient ill the fourth ankyrin domain. Hence, TIMAP targets PP-1 to LAMR1, and LAMR1 is a TIMAP-dependent PP-1 substrate. (c) 2005 Elsevier Inc. All rights reserved.