Variable N-terminal regions of muscle myosin heavy chain modulate ATPase rate and actin sliding velocity.
J Biol Chem
; 278(19): 17475-82, 2003 May 09.
Article
em En
| MEDLINE
| ID: mdl-12606545
ABSTRACT
We integratively assessed the function of alternative versions of a region near the N terminus of Drosophila muscle myosin heavy chain (encoded by exon 3a or 3b). We exchanged the alternative exon 3 regions between an embryonic isoform and the indirect flight muscle isoform. Each chimeric myosin was expressed in Drosophila indirect flight muscle, in the absence of other myosin isoforms, allowing for purified protein analysis and whole organism locomotory studies. The flight muscle isoform generates higher in vitro actin sliding velocity and solution ATPase rates than the embryonic isoform. Exchanging the embryonic exon 3 region into the flight muscle isoform decreased ATPase rates to embryonic levels but did not affect actin sliding velocity or flight muscle ultrastructure. Interestingly, this swap only slightly impaired flight ability. Exchanging the flight muscle-specific exon 3 region into the embryonic isoform increased actin sliding velocity 3-fold and improved indirect flight muscle ultrastructure integrity but failed to rescue the flightless phenotype of flies expressing embryonic myosin. These results suggest that the two structural versions of the exon 3 domain independently influence the kinetics of at least two steps of the actomyosin cross-bridge cycle.
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Coleções:
01-internacional
Temas:
Geral
Base de dados:
MEDLINE
Assunto principal:
Actinas
/
Adenosina Trifosfatases
/
Cadeias Pesadas de Miosina
Limite:
Animals
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
2003
Tipo de documento:
Article
País de afiliação:
Estados Unidos