The platelet protein kinase C substrate pleckstrin binds directly to SDPR protein.

Pleckstrin is a modular platelet protein consisting of N- and C-terminal pleckstrin homology (PH) domains, a central dishevelled egl10 and pleckstrin (DEP) domain and a phosphorylation region. Following agonist-induced platelet stimulation, dimeric pleckstrin translocates to the plasma membrane, is phosphorylated and then monomerizes. A recent study found that pleckstrin null platelets from a knockout mouse have a defect in granule secretion, actin polymerization and aggregation.

Proteomic identification of pleckstrin-associated proteins in platelets: possible interactions with actin.

Pleckstrin (plek)-null platelets from a knockout mouse have been shown to be defective in granule secretion, aggregation and actin polymerization. However, the mechanism of plek signaling is currently unknown. Therefore, we sought to identify plek-binding proteins in platelets by using GST pulldown assays and immunoprecipitation to isolate proteins from extracts of protein kinase C-activated or inhibited human platelets.

Structural analysis of the carboxy terminal PH domain of pleckstrin bound to D-myo-inositol 1,2,3,5,6-pentakisphosphate.

Background: Pleckstrin homology (PH) domains are one of the most prevalent domains in the human proteome and represent the major phosphoinositide-binding module. These domains are often found in signaling proteins and function predominately by targeting their host proteins to the cell membrane. Inositol phosphates, which are structurally similar to phosphoinositides, are not only known to play a role as signaling molecules but are also capable of being bound by PH domains.

Translocation of pleckstrin requires its phosphorylation and newly formed ligands.

Pleckstrin is the major substrate of protein kinase C (PKC) in platelets. We sought to determine whether pleckstrin phosphorylation is sufficient to target the soluble protein to binding sites. Permeabilization of platelets by streptolysin O (SLO) was used to separate bound and soluble pleckstrin.

Roles for both cyclic GMP and cyclic AMP in the inhibition of collagen-induced platelet aggregation by nitroprusside.

In studies on human platelets, nitroprusside (NP) alone at 1-10 micromol/l increased platelet cyclic AMP (cAMP) by 40-70%, whereas increases in cyclic GMP (cGMP) were much larger in percentage though not in concentration terms. Collagen enhanced these increases in cAMP up to fourfold, without affecting cGMP. This effect was partly prevented by indomethacin or aspirin, indicating that platelet cyclo-oxygenase products acted synergistically with NP to increase cAMP.

Cell-specific abnormal prenylation of Rab proteins in platelets and melanocytes of the gunmetal mouse.

The mutant gunmetal mouse exhibits reduced rates of platelet synthesis, abnormalities of platelet alpha and dense granules and hypopigmentation. Several of these features resemble those of human alpha/delta platelet storage pool disease, grey platelet syndrome and Hermansky-Pudlak syndrome. Gunmetal mice have reduced levels of Rab geranylgeranyltransferase (RabGGTase), which adds lipophilic prenyl groups to the carboxyl terminus of Rab proteins.

Molecular cloning, bacterial expression and properties of Rab31 and Rab32.

GTP-binding proteins of the Rab family were cloned from human platelets using RT-PCR. Clones corresponding to two novel Rab proteins, Rab31 and Rab32, and to Rab11A, which had not been detected in platelets previously, were isolated. The coding sequence of Rab31 (GenBank accession no.

Nitrolinoleate inhibits platelet activation by attenuating calcium mobilization and inducing phosphorylation of vasodilator-stimulated phosphoprotein through elevation of cAMP.

Reactive species formed from nitric oxide (NO) nitrate unsaturated fatty acids such as linoleate (LA) to nitrated derivatives including nitrolinoleate (LNO(2)). The effect of LNO(2) on human platelets was examined to define how nitrated lipids might behave in vivo. LNO(2), but not LA or 3-nitrotyrosine, dose dependently (0.