Presence in many mammalian tissues of an identical major cytosolic substrate (M r 100000) for calmodulin‐dependent protein kinase

FEBS Letters

Palfrey, H.Clive¹ 

[1] Department of Pharmacological and Physiological Sciences, University of Chicago, 947 E. 58th Street, Chicago, IL 60637, USA

关键词: Calcium;    Calmodulin;    Protein kinase;    Phosphorylase;    CaM;    calmodulin;    100 kDa;    major phosphoprotein of M r 100000;    EGTA;    ethylene glycol bis (β-aminoethylether)-N;    N;    N′;    N′-tetraacetic acid;    SAP;    Staphylococcus aureus protease;    SAC;    Staphylococcus aureus cells;   

DOI  :  10.1016/0014-5793(83)81142-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Incubation of cytosol fractions from a variety of mammalian tissues (heart, liver, lung, adrenal, spleen and skeletal muscle) with Ca²⁺ (0.5 mM) in the presence of γ-[³²P]ATP resulted in the phosphorylation of a prominent substrate of M _r ∼ 100000 (100 kDa). One-dimensional peptide maps and two-dimensional tryptic fingerprints of the phosphoprotein from these sources were identical. A single major phosphopeptide was generated by trypsin and was determined to contain exclusively phosphothreonine. The 100 kDa substrate could be distinguished from glycogen phosphorylase (M _r ∼ 97000) by a number of criteria including phosphopeptide mapping and by its failure to bind either to glycogen or to a specific antiphosphorylase antibody. The Ca²⁺-dependent protein kinase responsible for phosphorylation of the 100 kDa protein appeared to be a calmodulin (CaM)-requiring enzyme in that it could be inhibited in cytosol extracts by trifluoperazine (IC ₅₀ 6–16 μM) and that exogenous CaM was necessary for 100 kDa phosphorylation in CaM-depleted cytosol. These results suggest that a rise in intracellular Ca²⁺ resulting in an activation of CaM-dependent protein kinase leads to the phosphorylation of a common 100 kDa substrate in many tissues.

【 授权许可】

Unknown