The superfast human extraocular myosin is kinetically distinct from the fast skeletal IIa, IIb, and IId isoforms.

ABSTRACT: Humans express five distinct myosin isoforms in the sarcomeres of adult striated muscle (fast IIa, IId, the slow/cardiac isoform I/β, the cardiac specific isoform α, and the specialized extraocular muscle isoform). An additional isoform, IIb, is present in the genome but is not normally expressed in healthy human muscles. Muscle fibers expressing each isoform have distinct characteristics including shortening velocity. Defining the properties of the isoforms in detail has been limited by the availability of pure samples of the individual proteins. Here we study purified recombinant human myosin motor domains expressed in mouse C2C12 muscle cells. The results of kinetic analysis show that among the closely related adult skeletal isoforms, the affinity of ADP for actin·myosin (K(AD)) is the

SUBMITTER: Bloemink MJ 

PROVIDER: S-EPMC3779741 | biostudies-literature | 2013 Sep

REPOSITORIES: biostudies-literature