Phosphorylation of a tropomyosin-like (30 KD) protein during platelet activation

✍ Scribed by Lilly Y. W. Bourguignon; Seth Field; G. J. Bourguignon

• Book ID: 102878568
• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 793 KB
• Volume: 29
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/jcb.240290103

✦ Synopsis

In this study, we have used the tumor promoter 12-o-tetradecanoylphorbol-13acetate (TPA), as well as its biologically inactive analogue 4a-phorbol 12,13didecanoate (4cu-PDD), to investigate platelet protein phosphorylation and its possible correlation with platelet activation. Our data show that TPA, but not 4a-PDD, induces a preferential phosphorylation of a 30,000 dalton (30 KD) protein. This phosphoprotein is found to be physically associated with an actomyosincontaining platelet cytoskeleton complex. Further analysis using both standard two-dimensional gel electrophoresis and one-dimensional urea-SDS gel electrophoresis reveals that this 30 KD protein has several tropomyosin-like properties. Most importantly, the degree of TPA-induced phosphorylation of the 30 KD protein is directly proportional to the extent of platelet granule release and the shape change of the platelet, as well as to the degree of aggregation. We speculate that this phosphorylated tropomyosinlike protein may play a pivotal role in the regulation of actomyosin-mediated platelet contractility, which has been previously implicated in a variety of platelet functions.