Unphosphorylated twitchin forms a complex with actin and myosin that may contribute to tension maintenance in catch

被引：47

作者：

Funabara, Daisuke ^{[2
]}

Hamamoto, Chieko ^{[2
]}

Yamamoto, Koji ^{[2
]}

Inoue, Akinori ^{[2
]}

Ueda, Miki ^{[2
]}

Osawa, Rika ^{[2
]}

Kanoh, Satoshi ^{[2
]}

Hartshorne, David J. ^{[4
]}

Suzuki, Suechika ^{[3
]}

Watabe, Shugo ^{[1
]}

机构：

[1] Univ Tokyo, Grad Sch Agr & Life Sci, Bunkyo Ku, Tokyo 1138567, Japan

[2] Mie Univ, Grad Sch Bioresources, Tsu, Mie 5148507, Japan

[3] Kanagawa Univ, Fac Sci, Kanagawa 2591293, Japan

[4] Univ Arizona, Muscle Biol Grp, Tucson, AZ 85721 USA

来源：

JOURNAL OF EXPERIMENTAL BIOLOGY | 2007年 / 210卷 / 24期

关键词：

catch contraction; twitchin; ABRM; myosin; actin;

D O I：

10.1242/jeb.008722

中图分类号：

Q [生物科学];

学科分类号：

07 ; 0710 ; 09 ;

摘要：

Molluscan smooth muscle can maintain tension over extended periods with little energy expenditure, a process termed catch. Catch is thought to be regulated by phosphorylation of a thick filament protein, twitchin, and involves two phosphorylation sites, D1 and D2, close to the N and C termini, respectively. This study was initiated to investigate the role of the D2 site and its phosphorylation in the catch mechanism. A peptide was constructed containing the D2 site and flanking immunoglobulin (Ig) motifs. It was shown that the dephosphorylated peptide, but not the phosphorylated form, bound to both actin and myosin. The binding site on actin was within the sequence L10 to P29. This region also binds to loop 2 of the myosin head. The dephosphorylated peptide linked myosin and F-actin and formed a trimeric complex. Electron microscopy revealed that twitchin is distributed on the surface of the thick filament with an axial periodicity of 36.25 nm and it is suggested that the D2 site aligns with the myosin heads. It is proposed that the complex formed with the dephosphorylated D2 site of twitchin, F-actin and myosin represents a component of the mechanical linkage in catch.

引用

页码：4399 / 4410

页数：12

共 38 条

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