Identification of a troponin-I like protein in platelet preparations as histone H2B.
A tropomyosin-binding protein (app. Mr 17000) was detected in equine platelet preparations by a gel overlay technique. Its isolation, amino acid and partial sequence analyses have shown it to be histone H2B. As with a similar protein from pig platelet preparations [der Terrossian et al. (1983) FEBS Lett. 152, 202-206], it inhibits Mg2+-dependent actomyosin S1 ATPase. This inhibition is partially reversed in the presence of calmodulin and Ca2+ but is not potentiated, unlike troponin-I, by tropomyosin. This protein, along with the other histones, is almost certainly derived from a low level of contaminating nucleated cells in most platelet preparations.
D000595:Amino Acid Sequence; D000818:Animals; D001792:Blood Platelets / Q000032:analysis*; D002352:Carrier Proteins / Q000302:isolation & purification*; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D006657:Histones / Q000097:blood / Q000302:isolation & purification*; D009124:Muscle Proteins / Q000302:isolation & purification*; D014335:Tropomyosin / Q000378:metabolism*; D014336:Troponin / Q000097:blood / Q000302:isolation & purification*; D019210:Troponin I
D002352:Carrier Proteins; D006657:Histones; D009124:Muscle Proteins; D014335:Tropomyosin; D014336:Troponin; D019210:Troponin I