Phosphorylation of MYPT1 by protein kinase C attenuates interaction with PP1 catalytic subunit and the 20 kDa light chain of myosin.
The effect of phosphorylation in the N-terminal region of myosin phosphatase target subunit 1 (MYPT1) on the interactions with protein phosphatase 1 catalytic subunit (PP1c) and with phosphorylated 20 kDa myosin light chain (P-MLC20) was studied. Protein kinase C (PKC) phosphorylated threonine-34 (1 mol/mol), the residue preceding the consensus PP1c-binding motif ((35)KVKF(38)) in MYPT1(1-38), but this did not affect binding of the peptide to PP1c. PKC incorporated 2 mol P(i) into MYPT1(1-296) suggesting a second site of phosphorylation within the ankyrin repeats (residues 40-296). This phosphorylation diminished the stimulatory effect of MYPT1(1-296) on the P-MLC20 phosphatase activity of PP1c. Binding of PP1c or P-MLC20 to phosphorylated MYPT1(1-296) was also attenuated. It is concluded that phosphorylation of MYPT1 by PKC may therefore result in altered dephosphorylation of myosin.
Tóth
A
A
Department of Medical Chemistry, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary.
Kiss
E
E
Gergely
P
P
Walsh
M P
MP
Hartshorne
D J
DJ
Erdödi
F
F
D000818:Animals; D017089:Ankyrin Repeat / Q000502:physiology; D020134:Catalytic Domain; D008970:Molecular Weight; D018994:Myosin Light Chains / Q000378:metabolism*; D043263:Myosin-Light-Chain Phosphatase; D010455:Peptides / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D054645:Protein Phosphatase 1; D011817:Rabbits
D018994:Myosin Light Chains; D010455:Peptides; D011493:Protein Kinase C; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D043263:Myosin-Light-Chain Phosphatase