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Updated: Aug 9, 2026

Aip1p Dynamics Are Altered by the R256H Mutation in Actin
Published on: July 30, 2014
Myosin I mutants with only 1% of wild-type actin-activated MgATPase activity retain essential in vivo function(s)
X Liu1, N Osherov, R Yamashita
1Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 50, Room 2517, Bethesda, MD 20892, USA.
Abstract:
The single class I myosin (MYOA) of Aspergillus nidulans is essential for hyphal growth. It is generally assumed that the functions of all myosins depend on their actin-activated MgATPase activity. Here we show that MYOA mutants with no more than 1% of the actin-activated MgATPase activity of wild-type MYOA in vitro and no detectable in vitro motility activity can support fungal cell growth, albeit with a delay in germination time and a reduction in hyphal elongation. From these and other data, we conclude that the essential role(s) of myosin I in A. nidulans is probably structural, requiring little, if any, actin-activated MgATPase or motor activity, which have long been considered the defining characteristics of the myosin family.
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