Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ATPase activity of myosin-Is from lower eukaryotes is activated by phosphorylation by the p21-activated kinase family at the TEDS site on an actin-binding surface-loop. This actin-binding loop is the site of a cardiac myosin-II mutation responsible for some forms of familial hypertrophic cardiomyopathy. To determine the mechanism of myosin-I regulation by heavy-chain phosphorylation (HCP) and to better understand the importance of this loop in the function of all myosin isoforms, we performed a kinetic investigation of the regulatory mechanism of the Acanthamoeba myosin-IC motor domain (MIC(IQ)). Phosphorylated and dephosphorylated MIC(IQ) show actin-activated ATPase activity; however, HCP increases the ATPase activity >20-fold. HCP does not greatly affect the rate of phosphate release from MIC in the absence of actin, as determined by single turnover experiments. Additionally, HCP does not significantly affect the affinity of myosin for actin in the absence or presence of ATP, the rate of ATP-induced dissociation of actoMIC(IQ), the affinity of ADP, or the rate of ADP release. Sequential-mix single-turnover experiments show that HCP regulates the rate of phosphate release from actin-bound MIC(IQ). We propose that the TEDS-containing actin-binding loop plays a direct role in regulating phosphate release and the force-generating (A-to-R) transition of myosin-IC.
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PMID:Mechanism of regulation of Acanthamoeba myosin-IC by heavy-chain phosphorylation. 1236 35

2,3-Butanedione monoxime (BDM) is the well-characterized, low-affinity, non-competitive inhibitor of skeletal muscle myosin-II. It has been widely used at millimolar concentrations in cell biological experiments with the assumption that it is an ATPase inhibitor of the myosin superfamily. To determine the usefulness of BDM as a general myosin inhibitor, the ATPase activities of the motor domains of skeletal muscle myosin-II, Acanthamoeba myosin-IC, human myole, chicken myosin-V, and porcine myosin-VI were measured in the presence of 0-40 mM BDM. BDM inhibits skeletal muscle myosin-II, but it does not inhibit the ATPase activity of the other myosins. Therefore, BDM is not a general inhibitor of the myosin ATPase. BDM has a broad effect on many non-myosin proteins (many uncharacterized), and thus should not be used in whole-cell experiments as a myosin inhibitor.
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PMID:2,3-Butanedione monoxime (BDM) as a myosin inhibitor. 1263 Jul 4