Accessibility of Myofilament Cysteines and Effects on ATPase Depend on the Activation State during Exposure to Oxidants
Figure 1
Cysteines in isoforms of myofilament proteins.
A. Positions of cysteines in primary sequences of myofilament proteins from rat skeletal and cardiac muscles. Myofilament protein isoforms are represented by horizontal lines whose colors denote different muscle types: Actin has skeletal and cardiac isoforms; Tm is a dimer with alpha and beta isoforms; other myofilament proteins have fast-twitch (blue), slow-twitch (green), cardiac (red) and slow-twitch/cardiac (green/red) isoforms. Black circles denote cysteines conserved in at least two isoforms; white circles denote cysteines unique to a single isoform. Cysteine numbering is based on the rat primary sequences. The scale on the x-axis indicates approximate number of amino acids from the N-terminus for all myofilament proteins except *MHC, whose ∼1939 AA sequence had to be condensed to fit. B. Venn diagram showing number of cysteines expressed in cardiac, fast, or slow fiber types. Most myofilament cysteines are common to all three types, many are common to ventricular and slow skeletal but not fast skeletal muscle, and several are unique to fast skeletal muscle.