High pp60c-src level in human platelet dense bodies.
Phosphoproteins phosphorylated in vivo were examined in resting and thrombin-activated human blood platelets. Thrombin-stimulation resulted in an overall increase in labeled proteins containing phosphotyrosine. The most prominent was a protein of 60 Kd. By electroblotting, the 60 Kd protein was identified as the pp60c-src, the normal cellular homolog of the transforming protein of Rous sarcoma virus. We have examined the intracellular distribution of the pp60c-src within platelets. Use of immunoprecipitation and electrotransfer to study isolated membranes, alpha-granules, lysosomes, and dense granules (also termed dense bodies) revealed that pp60c-src was highly enriched in dense bodies. In view of the prominent role of these granules in platelet function, We postulate that protein phosphorylation by activated pp60c-src is involved in early steps of platelet activation.
Rendu
F
F
U150 INSERM, URA 184 CNRS.
Lebret
M
M
Danielian
S
S
Fagard
R
R
Levy-Toledano
S
S
Fischer
S
S
D001792:Blood Platelets / Q000378:metabolism* / Q000648:ultrastructure; D003594:Cytoplasmic Granules / Q000502:physiology; D006801:Humans; D008970:Molecular Weight; D010750:Phosphoproteins / Q000097:blood; D010766:Phosphorylation; D019000:Phosphotyrosine; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src); D013347:Subcellular Fractions / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D019000:Phosphotyrosine; D014443:Tyrosine; D016392:Proto-Oncogene Proteins pp60(c-src)