Evidence against the regulation of caldesmon inhibitory activity by p42/p44erk mitogen-activated protein kinase in vitro and demonstration of another caldesmon kinase in intact gizzard smooth muscle.
The effect of direct phosphorylation by recombinant p44erk1 mitogen-activated protein kinase on the inhibitory activity of caldesmon and its C-terminal fragment H1 was studied in vitro. Neither inhibition of actin-tropomyosin activated ATPase of heavy meromyosin by caldesmon or H1, nor inhibition of the actin-tropomyosin motility over heavy meromyosin by H1 was significantly affected by the phosphorylation while only a moderate effect on the actin-activated component of heavy meromyosin ATPase inhibition was observed. Phosphopeptide mapping of caldesmon immunoprecipitated from [32P]PO4-labelled intact gizzard strips revealed that it is predominantly phosphorylated at mitogen-activated protein kinase sites in unstimulated tissue and that it is stimulated for 1 h with phorbol 12,13-dibutyrate. We find that phorbol 12,13-dibutyrate also induces a transitory phosphorylation of caldesmon peaking at 15 min after addition and this phosphorylation is not attributed to mitogen-activated protein kinase, protein kinase C, Ca2+/calmodulin-dependent kinase II or casein kinase II. We suggest that a yet unidentified kinase, rather than mitogen-activated protein kinase, may be involved in regulation of the caldesmon function in vivo.
Krymsky
M A
MA
Laboratory of Cell Motility, Institute of Experimental Cardiology, Cardiology Research Center, Moscow, Russia.
Chibalina
M V
MV
Shirinsky
V P
VP
Marston
S B
SB
Vorotnikov
A V
AV
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D002645:Chickens; D005895:Gizzard, Avian / Q000201:enzymology; D007700:Kinetics; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D009130:Muscle, Smooth / Q000201:enzymology*; D010449:Peptide Mapping; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D010748:Phosphopeptides / Q000737:chemistry / Q000302:isolation & purification; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*
D002148:Calmodulin-Binding Proteins; D010748:Phosphopeptides; D015240:Phorbol 12,13-Dibutyrate; D011494:Protein Kinases; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C056959:caldesmon kinase; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases