This proposal will examine the structure and function of a 40 kDa protein in platelets which we believe to be the alpha subunit of a guanine nucleotide-binding regulatory protein or G protein. Based upon our recent studies, this protein has several novel properties. First, it is phosphorylated during platelet activation, apparently by protein kinase C. Second, it is immunologically cross-reactive with G(z-alpha), a putative alpha subunit that has been cloned from two non-platelet cDNA libraries, but not yet isolated. Third, in contrast to the other G proteins which have been a focus for platelet research, it is neither ADP-ribosylated by pertussis toxin nor recognized by antisera that are specific for known pertussis toxin-sensitive G proteins, such as G(i-alpha). Even though G(z- alpha) is not known to be a substrate for protein kinase C, we have provisionally named the platelet protein """"""""G(z-alpha)(plt)"""""""" in acknowledgement of the immunologic cross-reactivity of the two proteins. The goal of our studies will be to understand the structure and biology of G(z-alpha)(plt). Specifically, we will: (1) determine the identity of G(z- alpha)(plt) and define its relationship to G(z-alpha), (2) identify the sites at which G(z-alpha)(plt) is phosphorylated, (3) determine the biochemical consequences of phosphorylation and (4) define the role of G(z- alpha)(plt) in platelet function.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL045181-01
Application #
3364139
Study Section
Hematology Subcommittee 2 (HEM)
Project Start
1990-07-01
Project End
1995-06-30
Budget Start
1990-07-01
Budget End
1991-06-30
Support Year
1
Fiscal Year
1990
Total Cost
Indirect Cost
Name
University of Pennsylvania
Department
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Tong, Ming Han; Jiang, Hong; Liu, Ping et al. (2005) Spontaneous fetal loss caused by placental thrombosis in estrogen sulfotransferase-deficient mice. Nat Med 11:153-9
Woulfe, Donna; Jiang, Hong; Morgans, Alicia et al. (2004) Defects in secretion, aggregation, and thrombus formation in platelets from mice lacking Akt2. J Clin Invest 113:441-50
Brass, Lawrence F (2003) Thrombin and platelet activation. Chest 124:18S-25S
Prevost, N; Woulfe, D; Tognolini, M et al. (2003) Contact-dependent signaling during the late events of platelet activation. J Thromb Haemost 1:1613-27
Woulfe, Donna; Jiang, Hong; Mortensen, Richard et al. (2002) Activation of Rap1B by G(i) family members in platelets. J Biol Chem 277:23382-90
Yang, Jing; Wu, Jie; Jiang, Hong et al. (2002) Signaling through Gi family members in platelets. Redundancy and specificity in the regulation of adenylyl cyclase and other effectors. J Biol Chem 277:46035-42
Yang, J; Wu, J; Kowalska, M A et al. (2000) Loss of signaling through the G protein, Gz, results in abnormal platelet activation and altered responses to psychoactive drugs. Proc Natl Acad Sci U S A 97:9984-9
Fan, X; Brass, L F; Poncz, M et al. (2000) The alpha subunits of Gz and Gi interact with the eyes absent transcription cofactor Eya2, preventing its interaction with the six class of homeodomain-containing proteins. J Biol Chem 275:32129-34
Kowalska, M A; Ratajczak, J; Hoxie, J et al. (1999) Megakaryocyte precursors, megakaryocytes and platelets express the HIV co-receptor CXCR4 on their surface: determination of response to stromal-derived factor-1 by megakaryocytes and platelets. Br J Haematol 104:220-9
Brass, L F; Manning, D R; Cichowski, K et al. (1997) Signaling through G proteins in platelets: to the integrins and beyond. Thromb Haemost 78:581-9

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