Premium
Phosphorylation of telokin by cyclic nucleotide kinases and the identification of in vivo phosphorylation sites in smooth muscle
Author(s) -
MacDonald Justin A.,
Walker Lori A.,
Nakamoto Robert K.,
Gorenne Isabelle,
Somlyo Avril V.,
Somlyo Andrew P.,
Haystead Timothy A.J.
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)01884-6
Subject(s) - phosphorylation , in vivo , kinase , myosin light chain kinase , forskolin , chemistry , dephosphorylation , serine , protein phosphorylation , biochemistry , protein kinase a , microbiology and biotechnology , biology , phosphatase , in vitro
The Ca 2+ ‐independent acceleration of dephosphorylation of the regulatory light chain of smooth muscle myosin and relaxation of smooth muscle by telokin are enhanced by cyclic nucleotide‐activated protein kinase(s) [Wu et al. (1998) J. Biol. Chem. 273, 11362–11369]. The purpose of this study was to determine the in vivo site(s) and in vitro rates of telokin phosphorylation and to evaluate the possible effects of sequential phosphorylation by different kinases. The in vivo site(s) of phosphorylation of telokin were determined in rabbit smooth muscles of longitudinal ileum and portal vein. Following stimulation of ileum with forskolin (20 μM) the serine at position 13 was the only amino acid to exhibit increased phosphorylation. Rabbit portal vein telokin was phosphorylated on both Ser‐13 and ‐19 as a result of forskolin and GTPγS stimulation in vivo. Point mutation of Ser‐13 (to Ala or Asp) abolished in vitro phosphorylation by cyclic nucleotide‐dependent protein kinases.