Characterization of paramyosin and thin filaments in the smooth muscle of acorn worm, a member of hemichordates

In this study, we examined the muscle of a hemichordate, acorn worm, to clarify whether this animal is like echinoderms or like the other deuterostome animals. We found a 100-kDa protein in the smooth muscle of acorn worm. This protein was identified with paramyosin, since the purified protein formed paracrystals with a constant axial periodicity in the presence of divalent cations as paramyosin of other animals, showed ability to interact with myosin and shared common antigenicity with echinoderm paramyosin. On the other hand, troponin band was not detected in isolated thin filaments, and the filaments increased myosin-ATPase activity in a Ca2+-independent manner. The results indicate that troponin is lacking in thin filaments of acorn worm muscle just as in those of echinoderms. The muscle of hemichordate acorn worm is quite similar to echinoderm muscles, but different from chordate muscles.

Source: Journal of Biochemistry - December 1, 2016 Category: Biochemistry Authors: Sonobe, H., Obinata, T., Minokawa, T., Haruta, T., Kawamura, Y., Wakatsuki, S., Sato, N. Tags: Regular Papers Source Type: research