"Twitchin-actin linkage hypothesis" for the catch mechanism in molluscan muscles: evidence that twitchin interacts with myosin, myorod, and paramyosin core and affects properties of actomyosin.

"Twitchin-actin linkage hypothesis" for the catch mechanism in molluscan smooth muscles postulates in vivo existence of twitchin links between thin and thick filaments that arise in a phosphorylation-dependent manner [N.S. Shelud'ko, G.

Twitchin, a thick-filament protein from molluscan catch muscle, interacts with F-actin in a phosphorylation-dependent way.

Twitchin belongs to the titin-like giant proteins family, it is co-localized with thick filaments in molluscan catch muscles and regulates the catch state depending on its level of phosphorylation. The mechanism by which twitchin controls the catch state remains to be established. We report for the first time the ability of twitchin to interact with F-actin.