Loss of SM-B myosin affects muscle shortening velocity and maximal force development

Gopal J. Babu, Evgenij Loukianov, Tatiana Loukianova, Gail J. Pyne, Sabine Huke, George Osol, Robert B. Low, Richard J. Paul, Muthu Periasamy

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


We used an exon-specific gene-targeting strategy to generate a mouse model deficient only in the SM-B myosin isoform. Here we show that deletion of exon-5B (specific for SM-B) in the gene for the heavy chain of smooth muscle myosin results in a complete loss of SM-B myosin and switching of splicing to the SM-A isoform, without affecting SM1 and SM2 myosin content. Loss of SM-B myosin does not affect survival or cause any overt smooth muscle pathology. Physiological analysis reveals that absence of SM-B myosin results in a significant decrease in maximal force generation and velocity of shortening in smooth muscle tissues. This is the first in vivo study to demonstrate a functional role for the SM-B myosin isoform. We conclude that the extra seven-residue insert in the surface loop 1 of SM-B myosin is a critical determinant of crossbridge cycling and velocity of shortening.

Original languageEnglish (US)
Pages (from-to)1025-1029
Number of pages5
JournalNature Cell Biology
Issue number11
StatePublished - Nov 2001
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Cell Biology


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