Amino acid sequences of the cardiac L‐2A, L‐2B and gizzard 17 000‐ M r light chains of chicken muscle myosin

Myosins separated from various vertebrate muscles contain 2 heavy chains of -200 000-M, and 4 light chains of -20 OOOllcl, [l-4]. In connection with a relationship between the light chain structure and mechanism of the muscle contraction, we have studied the primary structures of the light chains of the fast skeletal, cardiac and gizzard muscle myosins from chicken [5-l 11. Chicken fast skeletal muscle myosin has 4 kinds of light chains designated L-l-L-4 in order of their increasing anionic mobilities at pH 8.3 [5,6,8-lo]. The L-l and L-4 light chains are also called alkali light chain 1 (Al) and alkali light chain 2 (A2), respectively. The L-2 and L-3 light chains are also known as DTNB light chains. L-3 is a phosphorylated L-2 light chain [l-3]. The primary structures of these light chains have been reported [5,6,8-lo]. Chicken cardiac muscle myosin has 2 kinds of light chains designated L-l and L-2, and the primary structure of the L-l light chain has been already reported [7,8]. We have also recognized 2 components in the L-2 light chain fraction by cellulogel electrophoresis at pH 8.3 after performic acid oxidation, and designated these components L-2A and L-2B. Chicken gizzard muscle myosin contains 2 kinds of light chains. One of them is called 20 000-M, light chain or GI light chain. It is also called regulatory light chain because it has calcium binding ability [4]. The other is called 17 000-M, light chain or GII light chain [4]. The primary structure of the 20 000-M, light chain has been reported [ 111. Here, we present the primary structures of the