Open AccessRequirement of the 20‐kDa light chain for the papain‐resistant conformation of gizzard myosin
Author(s) -
KUMON Akira,
YASUDA Seiji,
MURAKAMI Noriko,
TASHIRO Yuko,
MATSUMURA Sueo
Publication year - 1984
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1984.tb08511.x
Subject(s) - gizzard , papain , immunoglobulin light chain , myosin , chemistry , heavy chain , chain (unit) , stereochemistry , biophysics , biochemistry , biology , enzyme , genetics , physics , gene , antibody , ecology , astronomy
1 The limited chymotryptic digestion of unphosphorylated gizzard myosin in 0.15 M NaCl converted a papain‐insensitive myosin in ATP to a papain‐sensitive one. This conversion without phosphorylation of its 20‐kDa light chain was accompanied with truncation of a 200‐kDa heavy chain to a 195‐kDa fragment and with the degradation of a 20‐kDa light chain. 2 Papain also yielded the 195‐kDa fragment from the heavy chain, irrespective of the presence or absence of ATP. However, the ATP‐induced protection of unphosphorylated myosin from the papain‐digestion disappeared concurrently with degradation of the 20‐kDa light chain by papain rather than the truncation of heavy chain. 3 Papers from two laboratories [Onishi, H. & Watanabe, S. (1984) J. Biochem. (Tokyo) 95 , 903–905; Kumon, A., Yasuda, S., Murakami, N., and Matsumura, S. (1984) Eur. J. Biochem. 140 , 265–271] have reported that the ATP‐protection of unphosphorylated myosin against papain is not observed after the 20‐kDa light chain has been phosphorylated. The present results might indicate that the ATP‐induced protection is also abolished through the chymotryptic degradation of the 20‐kDa light chain.