Open AccessPartial purification and characterization of a 60000‐dalton phosphoprotein from pig heart tissue
Author(s) -
DAVIDPFEUTY Thérèse,
HOVANESSIAN Ara
Publication year - 1984
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1984.tb08106.x
Subject(s) - phosphoprotein , rous sarcoma virus , proteases , serine , chemistry , threonine , fractionation , biochemistry , hydrolysis , chromatography , phosphorylation , enzyme , gene
A 60000‐dalton phosphoprotein (pp60) was purified up to 10 4 ‐fold by a combination of low‐ionic‐strength extraction, ammonium sulfate fractionation, on‐exchange and affinity chromatography, all in detergent‐free buffer. Fractionation on ω‐aminohexylagarose column shows that pp60 actually consists of two different polypeptides of similar molecular mass (pp60 ω1 and pp60 ω2 ). Partial hydrolysis with proteases of the proteins 32 P‐labeled in vitro indicates that pp60 ω1 and pp60 ω2 are similar but not identical. On the other hand, individual phosphoamino acid analysis reveals that pp60 ω1 is phosphorylated primarily at serine residues while pp60 ω1 is phosphorylated almost equally at serine and threonine residues. Partial hydrolysis with proteases has been also used to explore a possible relationship between the pp60's and the transforming protein of Rous sarcoma virus (pp60 v‐src ). Our data suggest that pp60 v‐src also consists of two different polypeptides chemically homologous to the presently purified pp60's.