当前位置： SCI文献检索 > LIFE SCIENCES期刊下所有文献 > Differential inhibition by alpha and epsilonPKC pseudosubstrate sequences: a putative mechanism for preferential PKC activation in neonatal cardiac myocytes.

Differential inhibition by alpha and epsilonPKC pseudosubstrate sequences: a putative mechanism for preferential PKC activation in neonatal cardiac myocytes.

Abstract：

:The aims of the current study were: 1) to determine if the epsilonPKC pseudosubstrate peptide (epsilonphi) (NH(2)-RKRQGAVRRRVHQVNG-COOH) could be used as an epsilonPKC-selective inhibitor in neonatal cardiac myocytes (NCMs) and 2) to determine if differences in the alpha and epsilonPKC autoinhibitory pseudosubstrate mechanisms could play roles in alpha and epsilonPKC-selective functions. Introduction of the epsilonphi into NCMs by transient permeabilization modestly attenuated 3 nM 4-beta PMA-induced slowing of contraction rate, an epsilonPKC mediated response (Circ Res. 76:654-663; J. Biol. Chem. 271:24962-24966). In contrast, the alphaPKC pseudosubstrate peptide (alphaphi) (NH(2)-RFARKGALRQKNVHEVK-COOH) was 6- to 10-fold more potent at antagonizing the 3 nM 4-beta PMA-induced slowing of contraction rate. Addition of purified PKC to the particulate cell fraction of NCMs promoted (32)P incorporation into 3 proteins of approximately 18, approximately 46 and approximately 97 kDa. The alphaphi antagonized these phosphorylations with IC(50) values of 1 - 5 microM. These IC(50) values were 1.8 - 4.7-fold lower than those observed for the epsilonphi. In in vitro phosphorylation assays with recombinant alpha or epsilon PKC isozymes the phi failed to inhibit the PKC isozyme as potently as the alphaphi peptide but both the alphaphi and the epsilonphi were equally effective inhibitors of the recombinant alphaPKC isozyme. In addition, in vitro cleavage of the epsilonphi by the protease Arg-C in lysates from NCMs treated with 3 nM 4-beta PMA was greatly enhanced when compared to that of the alphaPKC isozyme. Our studies suggest that the epsilonphi cannot be used as a selective inhibitor of the epsilonPKC isozyme in NCMs and that there are differences in the epsilonPKC and alphaPKC autoinhibitory pseudosubstrate mechanisms.

journal_name

Life Sci

journal_title

Life sciences

authors

Johnson JA

doi

10.1016/j.lfs.2003.11.016

subject

Has Abstract

pub_date

2004-05-07 00:00:00

pages

3153-72

issue

eissn

0024-3205

issn

1879-0631

pii

S0024320504001638

journal_volume

pub_type

杂志文章

在线工具

Differential inhibition by alpha and epsilonPKC pseudosubstrate sequences: a putative mechanism for preferential PKC activation in neonatal cardiac myocytes.