Contraction induced by antibodies to paramyosin in glycerinated fibers of Barnacle giant muscle in an ATP-deficient medium: a possible function of paramyosin.

Glycerinated giant muscle fibers of the barnacle Balanus rostratus in an ATP-deficient solution respond to antibodies to paramyosin (aPM) by an isometric tension development followed by an immediate spontaneous relaxation. The aPM presence does not affect the subsequent contraction and relaxation of the fibers in suitable ATP-containing media. The effects of ATP and aPM present together in a contracting medium are additive. The aPM effect is caused assumedly by a sudden shortening of some highly elastic connecting filaments which are linked in a stretched and strained state to the thick filament by its paramyosin, aPM dissociates this link. Possible specific functions of paramyosin in various types of muscles are discussed.