title: Sulfation of guinea pig megakaryocyte and platelet proteins.
abstract: This study has explored the sulfation of proteins by guinea pig megakaryocytes and platelets and by human platelets. Guinea pig megakaryocytes were incubated in vitro with [35S]sulfate, and the sulfated proteins were separated from proteoglycans by DEAE-Sephacel chromatography and analyzed by SDS-PAGE. The megakaryocytes esterified sulfate to a number of proteins, with the most extensive label migrating at M(r) 42,000, and a second heavily labeled band at M(r) 103,000 in the 0.1 M NaCl DEAE eluate, and 50 and 180 kDa in the 0.23 M NaCl eluate. [35S]-Labeled GPlb alpha was immunoprecipitated from megakaryocyte Triton X-100 extracts. Guinea pig platelet proteins were labeled in vivo by injection of the animals with a single dose of H2(35)SO4. The platelets were activated with thrombin, and cytoskeletal proteins were isolated after treatment of the activated platelets with Triton X-100. About 20% of the platelet macromolecule-associated [35S]sulfate was incorporated into sulfated proteins, which were recovered primarily in the cytoskeleton. The cytoskeleton-associated sulfate radiolabel migrated on SDS-PAGE primarily with actin and additionally with several higher molecular weight proteins. A M(r) 42,000 [35S]-labeled protein was immunoprecipitated by a monoclonal anti-actin antibody, along with molecules of M(r) 160,000 and 180,000 and some higher M(r) material, from the megakaryocytes labeled in vitro with [35S]sulfate. Actin was labeled on 2D isoelectric focusing/SDS-PAGE gels. In addition, there was a very acidic series of heavily [35S]-labeled 42 kDa proteins with about eight components of different isoelectric points with a pattern identical to the M(r) 40,000 cytoskeletal-associated glycoprotein Pltpg40 isolated by Hildreth et al. (1991, Blood 77:121). We hypothesize that sulfation of the cytoskeletal proteins might be involved in cytoskeletal protein interactions and function.
authors.affiliation: Cardeza Foundation for Hematologic Research, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania 19107.
authors.forename: B P
authors.initials: BP
authors.lastname: Schick
authors.forename: J A
authors.initials: JA
authors.lastname: Jacoby
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D001792:Blood Platelets / Q000378:metabolism*; D001798:Blood Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism; D006168:Guinea Pigs; D008297:Male; D008533:Megakaryocytes / Q000378:metabolism*; D011233:Precipitin Tests; D013431:Sulfates / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D000199:Actins; D001798:Blood Proteins; D013431:Sulfates