p42 MAPK phosphorylates 80 kDa MARCKS at Ser-113.
Abstract It is demonstrated here that p42 MAPKinase (p42 MAPK) phosphorylates the M yristoylated A lanine- R ich C - K inase S ubstrate (MARCKS) at Ser-113. In permeabilised Swiss 3T3 cells activation of protein kinase C (PKC) leads to p42 MAPK activation, but only the protein kinase C sites in MARCKS become phosphorylated and not Ser-113. The mitogen platelet-derived growth factor (PDGF) elicits the same response. These results demonstrate that while Ser-113 is a substrate for p42 MAPK in vitro and can be phosphorylated in vivo as shown by Taniguchi et al. [(1994) J. Biol. Chem. 269, 18299–18302], its phosphorylation is not subject to acute regulation by p42 MAPK in Swiss 3T3 cells.
The Myristoylated Alanine-Rich C-Kinase Substrate (MARCKS) is Sequentially Phosphorylated by Conventional, Novel and Atypical Isotypes of Protein Kinase C
The myristoylated alanine-rich C-kinase substrate (MARCKS) is the major protein kinase C (PKC) substrate in many cell types including fibroblasts and brain cells. Here we describe the phosphorylation of MARCKS and the site specificity for different PKC isotypes. Conventional (c)PKC beta 1, novel (n)PKC delta and nPKC epsilon efficiently phosphorylated the MARCKS protein in vitro. The Km values were extremely low, reflecting a high affinity between kinases and substrate. The apparent affinity of nPKC delta (Km = 0.06 microM) was higher than that of nPKC epsilon and cPKC beta 1 (Km = 0.32 microM). The rate of substrate phosphorylation was inversely correlated with affinity and decreased in th…
Phosphorylation of GAP-43 (growth-associated protein of 43 kDa) by conventional, novel and atypical isotypes of the protein kinase C gene family: differences between oligopeptide and polypeptide phosphorylation
GAP-43 (growth-associated protein of 43 kDa; also known as neuromodulin, P-57, B-50 and F-1) is a neuronal calmodulin binding protein and a major protein kinase C (PKC) substrate in mammalian brain. Here we describe the phosphorylation by and the site specificity of different PKC isotypes. The conventional PKC beta 1 and the novel PKCs delta and epsilon effectively phosphorylated recombinant GAP-43 in vitro; atypical PKC zeta did not. The K(m) values (between 0.6 and 2.3 microM) were very low, demonstrating a high-affinity interaction between kinase and substrate. All PKC isotypes were shown to phosphorylate serine-41 in GAP-43. When using a 19-amino-acid oligopeptide based on the GAP-43 ph…
PRK1 phosphorylates MARCKS at the PKC sites: serine 152, serine 156 and serine 163
AbstractThe 80kDa Myristolated Alanine-Rich C-Kinase Substrate (MARCKS) in a major in vivo substrate of protein kinase C (PKC). Here we report that MARCKS is a major substrate for the lipid-activated PKC-related kinase (PRK1) in cell extracts. Furthermore, PRK1 is shown to phosphorylate MARCKS on the same sites as PKC in vitro. Thus, control of MARCKS phosphorylation on these previously identified ‘PKC’ sites may be regulated under certain circumstances by PRK as well as PKC mediated signalling pathways. The implications for MARCKS as a marker of PKC activation and as a point of signal convergence are discussed.
MET-EGFR dimerization in lung adenocarcinoma is dependent on EGFR mtations and altered by MET kinase inhibition
Advanced lung cancer has poor survival with few therapies. EGFR tyrosine kinase inhibitors (TKIs) have high response rates in patients with activating EGFR mutations, but acquired resistance is inevitable. Acquisition of the EGFR T790M mutation causes over 50% of resistance; MET amplification is also common. Preclinical data suggest synergy between MET and EGFR inhibitors. We hypothesized that EGFR-MET dimerization determines response to MET inhibition, depending on EGFR mutation status, independently of MET copy number. We tested this hypothesis by generating isogenic cell lines from NCI-H1975 cells, which co-express L858R and T790M EGFR mutations, namely H1975L858R/T790M (EGFR TKI resista…