The amino acid sequence and stability predictions of the hinge region in myosin subfragment 2.

From an NH2-terminal sequence analysis of the long and short form of myosin subfragment 2 we have suggested that the putative hinge region in the myosin rod is located in the COOH-terminal portion of the long subfragment 2 (Lu, R. C. (1980) Proc. Natl. Acad. Sci. U.S.A. 77, 2010-2013). The amino acid sequence of this hinge region has now been determined: ASRA KAEKQRSDLSRELEEISERLEEAGGATSAQIEMNK KREAEFEKMRRDLEEATLQHEATAAALRKKHAD SVAELGEQIDNLQRVKQKLEKEKSELKMEIDDLA GNMETVSKAKGNLEKMCRTLEDQ(L/V)SE(V/L)KT KEEEHQRLIN(D/E)L(S/G)AQ(K/R)AR. Comparison of the sequence with that of other portions of the rod, viz. short subfragment 2 and light meromyosin, and of tropomyosin shows that the hinge region shares some feature of a coiled-coil helical structure, but it has somewhat fewer hydrophobic coil-coil interactions and there is a significant number of charged residues in the hydrophobic core region. This suggests that the stability of the putative hinge region would be reduced in comparison with other coiled-coil structures.