Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.4.1 (myosin ATPase)
 1,140 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The regulatory domain of smooth muscle myosin light chain kinase (MLCK) was studied using monoclonal antibodies. Of the 22 monoclonal antibodies tested, a monoclonal antibody designated LKH-18 was found to activate MLCK in the absence of Ca2+/calmodulin. This activation was even greater when an Fab fragment of LKH-18 was used. Consequently, the actin-dependent smooth muscle myosin ATPase activity and the superprecipitation of actomyosin were significantly activated by MLCK plus LKH-18, even in the absence of Ca2+/calmodulin. The antibody-binding site was studied using proteolytic fragments and synthetic peptide analogues of MLCK. Immunoblot analysis revealed that LKH-18 reacted with the 66 kDa calmodulin-dependent active fragment but not with the 64 kDa inactive fragment or with the 61 kDa calmodulin-independent active fragment. Furthermore, LKH-18 reacted with MLCK-(796-815)-peptide but not with MLCK-(786-801)-peptide or with MLCK-(796-807)-peptide. Therefore the LKH-18-binding site was assigned to amino acid residues 808-815 of MLCK, which are thought to be a part of the calmodulin-binding site. The present results suggest that the binding of ligand to this region induces a conformation change in MLCK and that this abolishes the action of the inhibitory region which exists next to the N-terminal side of the calmodulin-binding site.
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PMID:Activation of smooth muscle myosin light chain kinase activity by a monoclonal antibody which recognizes the calmodulin-binding region. 171 Jan 6