Effects of Clam-Foot Paramyosin, Tropomyosin, and Rabbit Skeletal Light-Meromyosin on the ATPase and Superprecipitation Activities of Actomyosin1

Abstract

1. Clam-foot paramyosin strongly inhibited superprecipitation of clam-foot actomyosin whereas it did not at all affect its ATPase reaction. On the other hand, superprecipitation of rabbit actomyosin and its ATPase reaction were both inhibited by clam foot paramyosin. 2. Clam-foot paramyosin did not at all affect the Mg-ATPase activity of clam-foot myosin alone (with no actin) but inhibited that of rabbit skeletal myosin alone. 3. Clam-foot paramyosin did not affect the ATPase reaction of rabbit acto-clam myosin but inhibited its superprecipitation. In other words, the effect of paramyosin on the ATPase reaction of actomyosin was simply dependent on the myosin source. 4. Clam-foot tropomyosin slightly enhanced superprecipitation of clam-foot actomyosin and scarcely affected its ATPase reaction, but it inhibited the reactions both of skeletal actomyosin and of rabbit acto-clam myosin. 5. Rabbit skeletal light-meromyosin (LMM) inhibited the ATPase and superprecipitation reactions of rabbit skeletal actomyosin, but it scarcely affected the ATPase reaction of rabbit acto-clam myosin while inhibiting its superprecipitation. In other words, rabbit LMM behaved the same way as clam paramyosin did. 6. Speculating on these findings and our previous findings, we suggest that the formation of a certain filamentous structure is the essential link between the ATPase reaction and contraction in molluscan muscles.

Invertebrate muscles: Thin and thick filament structure; molecular basis of contraction and its regulation, catch and asynchronous muscle

“…A large number of papers deal with isolation and initial characterization (e.g., Ca ++ and ATP dependence, heavy and light chain complement) of molluscan actomyosin (Lajtha, 1947;Humphrey, 1948Humphrey, , 1949Weber, 1953;Matsumoto, 1954, 1957;Weber and Portzehl, 1954;de Villafranca, 1955;Tonomura et al, 1955Tonomura et al, , 1956Bailey, 1956;Strelina et al, 1957;Matsumoto, 1957;Maruyama, 1957bMaruyama, , 1958aMatsumoto, 1958aMatsumoto, -d, 1959Kishimoto, 1961;Bárány and Bárány, 1966;Schädler, 1967;Mognoni and Lanzavecchia, 1969;Twarog and Muneoka, 1972;Horie et al, 1975;Azuma et al, 1975;Azuma, 1976;Nishita, 1977;Nishita et al, 1977Nishita et al, , 1979Tsuchiya et al, 1978b-d;Asada et al, 1979;Toyo-Oka, 1979;Tanaka and Tanaka, 1979a,b;Ashiba et al, 1980Ashiba et al, , 1982Kimura et al, 1980;Asakawa, 1980;Stephenson and Williams, 1980;Morita and Kondo, 1982;Szent-Györgyi and Niebieski, 1982;Yoshitomi and Konno, 1982;Krause and Munson, 1982;Kodama and Konno, 1983...…”

Biochemical properties of akazara scallop myosin hybridized with the foreign regulatory light chains.

“…Ashiba et al,10) found that the Mg-ATPase acti vity of clam foot myosin alone is as sensitive as that of skeletal acto-clam foot myosin, and that the desensitization of clam foot myosin is accompanied by the reversible loss of superprecipitation activity of the actomyosin. From these findings, they proposed that the primary role of the regulatory light chain in Call-regula tion is to inhibit myosin ATPase activity not actin-myosin interaction, and the secondary role is to maintain the conformation of myosin heads which is essential for actin-myosin inter action.11) Thereafter, these findings were confirmed with myosins from squid Todarodes pacifzcus,12) ezo-giant scallop, 12) akazara scallop, [13][14][15][16][17] and surf-clam Spisula sacharinen sis,18) and extended to the tension development …”

Comparative Biochemistry of Paramyosin?a Review

“…While associated, the muscle is able to maintain the developed tension. However, Nonomura (1974) as well as Ashiba et al (1982) were unable to confirm the observations made by Szent-Gyorgyi et al (1971). Instead, they showed that the paramyosin slightly enhances the Mg-ATPase activity rather than inhibiting it.…”

“…This research group, however, did not specify the clam species used in their study. Recently, Konno et al (1988), using squid (Todarodespacijicus), reported that they could not confirm the findings of Ashiba et al (1982) that the effect of paramyosin on the ATPase activity depends on the source of myosin. As one must note, the observations of Szent-Gyorgyi et al (1971), Nonomura (1974), Ashiba et al (1982) and Konno el al.…”

“…Mention should also be made that, Szent-Gyorgyi et al (1971) and Nonomura (1974) had used Mercenaria mercenaria and Meretrix lamarckii, respectively. Ashiba et al (1982) had observed that: ( 1 ) the effect of clam-foot paramyosin on the ATPase activity depends on the source of myosin, i.e., whether the type investigated was from clam or rabbit; and (2) the effects of paramyosin, under the experimental conditions employed by them, was independent of the state of phosphorylation of the molecule. This research group, however, did not specify the clam species used in their study.…”