PMID- 1322916
OWN - NLM
STAT- MEDLINE
DCOM- 19920910
LR  - 20210210
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 267
IP  - 23
DP  - 1992 Aug 15
TI  - Purification and characterization of smooth muscle myosin-associated phosphatase 
      from chicken gizzards.
PG  - 16727-35
AB  - Myosin light chain phosphatase associated with smooth muscle myosin (MAPP) was 
      isolated from chicken gizzard. The MAPP was tightly associated with myosin and 
      was not dissociated from myosin under the physiological ionic conditions. The 
      phosphatase was dissociated from myosin in the presence of high MgCl2, i.e. 80 mM 
      MgCl2. The binding site of the enzyme on the myosin molecule was the 
      subfragment-2 region, since the enzyme did bind to the myosin rod and heavy 
      meromyosin but not to the subfragment-1 affinity column. MAPP was purified with a 
      heparin-Sepharose 6B column, and two activity peaks were obtained, i.e. MAPP I 
      and MAPP II. The major activity peak, MAPP I, was further purified to homogeneity 
      by thiophosphorylated myosin light chain-Sepharose 4B column chromatography. MAPP 
      I was a tetramer composed of four 34-kDa subunits. The enzyme preferentially 
      dephosphorylated the beta-subunit of phosphorylase kinase and was strongly 
      inhibited by the heat- and acid-stable protein phosphatase inhibitor-1, whereas 
      it was partially inhibited by the inhibitor-2. The IC50 (concentration of 
      inhibitor giving 50% inhibition) value for the inhibition of the enzyme by 
      okadaic acid was 70 nM which was about eight times higher than skeletal muscle 
      type-1 and 390 times higher than type-2 protein phosphatase. These results 
      demonstrate that the MAPP I is a type-1-like protein phosphatase, although the 
      properties are not the same as type-I phosphatase. The properties of the 
      myosin-associated phosphatase were distinct from the phosphatases reported 
      previously, although some properties were similar to smooth muscle 
      phosphatase-IV. Therefore, it is concluded that MAPP I is a novel smooth muscle 
      protein phosphatase. Since it strongly associated with smooth muscle myosin, it 
      is likely that MAPP I is responsible for the dephosphorylation of smooth muscle 
      myosin in situ.
FAU - Mitsui, T
AU  - Mitsui T
AD  - Department of Physiology and Biophysics, Case Western Reserve University, 
      Cleveland, Ohio 44106-4970.
FAU - Inagaki, M
AU  - Inagaki M
FAU - Ikebe, M
AU  - Ikebe M
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - J Biol Chem
JT  - The Journal of biological chemistry
JID - 2985121R
RN  - 0 (Ethers, Cyclic)
RN  - 0 (Phosphorus Radioisotopes)
RN  - 1W21G5Q4N2 (Okadaic Acid)
RN  - 8L70Q75FXE (Adenosine Triphosphate)
RN  - EC 3.1.3.16 (Phosphoprotein Phosphatases)
RN  - EC 3.1.3.53 (Myosin-Light-Chain Phosphatase)
SB  - IM
MH  - Adenosine Triphosphate/metabolism
MH  - Animals
MH  - Chickens
MH  - Chromatography, Affinity
MH  - Chromatography, Gel
MH  - Electrophoresis, Polyacrylamide Gel
MH  - Enzyme Stability
MH  - Ethers, Cyclic/pharmacology
MH  - Gizzard, Avian/*enzymology
MH  - Kinetics
MH  - Muscle, Smooth/*enzymology
MH  - Myosin-Light-Chain Phosphatase
MH  - Okadaic Acid
MH  - Phosphoprotein Phosphatases/antagonists & inhibitors/*isolation & 
      purification/*metabolism
MH  - Phosphorus Radioisotopes
MH  - Substrate Specificity
EDAT- 1992/08/15 00:00
MHDA- 1992/08/15 00:01
CRDT- 1992/08/15 00:00
PHST- 1992/08/15 00:00 [pubmed]
PHST- 1992/08/15 00:01 [medline]
PHST- 1992/08/15 00:00 [entrez]
AID - S0021-9258(18)42062-5 [pii]
PST - ppublish
SO  - J Biol Chem. 1992 Aug 15;267(23):16727-35.