title: Increase in phosphotidylinositide-3 kinase activity by nitrotyrosylation of lysates of platelets from patients with systemic sclerosis.
abstract: We have observed that the platelet non-integrin collagen receptor (65 kDa) and another protein (M(r) 185 kDa) are altered in the posttranslational modification by nitrotyrosylation in platelets from patients with systemic sclerosis (SSc). We reported the identification of nitrotyrosylated 65-kDa proteins in a previous study. In the present investigation, using Western blots, one- and two-dimensional gel electrophoreses and matrix assisted ionization/desorption-time of flight (MALDI-TOF) we have identified the 185-kDa protein as phosphoinositide kinase C2beta (PI 3-K). There is a positive correlation between the nitrotyrosylation of PI 3-K and activity of the enzyme, i.e., the nitrotyrosylation of PI 3-K increases its enzymatic activity. In addition, the activity of PI 3-K increases in nitrotyrosylated platelet lystaes from patients with SSc compared to normal volunteer controls, suggesting that this is an alteration in the posttranslational modification of PI 3-K in platelets from patients with SSc. The increased nitrotyrosylation of PI 3-K may contribute to the impairment of platelet function in patients with SSc by increasing platelet reactivity to matrix components within the vascular walls of patients with this disease.
authors.affiliation: Research Service (151), Veterans Affairs Medical Center, 1030 Jefferson Avenue, Memphis, TN 38104, USA. tchiang@utmem.edu
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Chiang
authors.forename: Arnold E
authors.initials: AE
authors.lastname: Postlethwaite
mesh_terms: D000328:Adult; D001792:Blood Platelets / Q000201:enzymology*; D016022:Case-Control Studies; D002474:Cell-Free System; D058541:Class II Phosphatidylinositol 3-Kinases; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D019869:Phosphatidylinositol 3-Kinases / Q000032:analysis / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D012595:Scleroderma, Systemic / Q000097:blood / Q000201:enzymology*; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: C002744:3-nitrotyrosine; D014443:Tyrosine; D019869:Phosphatidylinositol 3-Kinases; D058541:Class II Phosphatidylinositol 3-Kinases; C502616:PIK3C2B protein, human