M. Okano et al., Biochemical characterization of cholesterol-3-sulfate as the sole effectorfor the phosphorylation of HMG1 by casein kinase I in vitro, BIOC BIOP R, 281(5), 2001, pp. 1325-1330
Citations number
31
Categorie Soggetti
Biochemistry & Biophysics
Journal title
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
Phosphorylation of high mobility group protein 1 (HMG1) by casein kinase I
(CK-I) and potent effecters (inhibitors and activators) of this phosphoryla
tion were investigated in vitro. We found that (i) CK-I phosphorylates spec
ifically threonine residues on HMG1 when incubated with cholesterol-3-sulfa
te (CH-3S), but no phosphorylation of HMG1 is detected in the presence of o
ther cholesterol related compounds or their sulfated derivatives; (ii) this
phosphorylation is selectively inhibited by heparin, but stimulated signif
icantly by 3 ' ,4 ' ,7-trihydroxy-isofavone at low doses (0.1-3 muM); and (
iii) CH-3S directly induces a drastic conformational change in HMG1. The la
tter finding provides a mechanism to explain how CH-SS alone can induce the
phosphorylation of HMG1 by CK-I in vitro. (C) 2001 Academic Press.