Identification of the endogenous smooth muscle myosin phosphatase-associated kinase.
Ca(2+) sensitization of smooth muscle contraction involves inhibition of myosin light chain phosphatase (SMPP-1M) and enhanced myosin light chain phosphorylation. Inhibition of SMPP-1M is modulated through phosphorylation of the myosin targeting subunit (MYPT1) by either Rho-associated kinase (ROK) or an unknown SMPP-1M-associated kinase. Activated ROK is predominantly membrane-associated and its putative substrate, SMPP-1M, is mainly myofibrillar-associated. This raises a conundrum about the mechanism of interaction between these enzymes. We present ZIP-like kinase, identified by "mixed-peptide" Edman sequencing after affinity purification, as the previously unidentified SMPP-1M-associated kinase. ZIP-like kinase was shown to associate with MYPT1 and phosphorylate the inhibitory site in intact smooth muscle. Phosphorylation of ZIP-like kinase was associated with an increase in kinase activity during carbachol stimulation, suggesting that the enzyme may be a terminal member of a Ca(2+) sensitizing kinase cascade.
Duke Scholars
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- Rabbits
- Protein Serine-Threonine Kinases
- Precipitin Tests
- Phosphorylation
- Muscle, Smooth
- Molecular Sequence Data
- Electrophoresis, Polyacrylamide Gel
- Death-Associated Protein Kinases
- Chromatography, Ion Exchange
- Cattle
Citation
Published In
DOI
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- Rabbits
- Protein Serine-Threonine Kinases
- Precipitin Tests
- Phosphorylation
- Muscle, Smooth
- Molecular Sequence Data
- Electrophoresis, Polyacrylamide Gel
- Death-Associated Protein Kinases
- Chromatography, Ion Exchange
- Cattle