Thin-filament-associated proteins implicated in the regulation and modulation of smooth muscle contraction. They will bind actin, calmodulin, troponin C, and tropomyosin and will inhibit myosin ATPase activity when not phosphorylated. Various isoforms are known: calponin-1 (calponin H1, basic calponin, 297 aa), calponin-2 (calponin H2, neutral calponin, 309 aa), calponin-3 (acidic calponin, 329 aa). Calponin homology domains (CH domains) are actin-binding domains found in cytoskeletal and signal transduction proteins; actinin-type actin-binding domain are a subclass of the CH domains.
Subjects: Medicine and Health — Chemistry.