Saturday 3 June 2006
Specific myosins are implicated in sensory transduction.
Mutations in the genes encoding myosin-VI and myosin-VIIa have been linked to several disorders characterized by deafness in humans.
The strongest evidence of a defect in vesicular transport in this group of diseases is found in Usher syndrome type 1B, which is caused by mutations in the gene for myosin-VIIa.
In addition to deafness, patients with this syndrome have retinitis pigmentosa, which leads to blindness.
Myosin-VIIa is abundant in the synaptic regions of photoreceptor cells and presumably acts as an actin-based motor protein involved in the formation and transport of the ribbon-synaptic vesicle complexes characteristic of these sensory cells.
Furthermore, myosin-VIIa may be involved in the renewal of the outer photoreceptor disks, a process requiring efficient membrane transport, and in endocytic transport in cochlear hair cells.
vesicula transport (vesicle transport)
- cadherin-associated deafness
Olkkonen VM, Ikonen E. Genetic defects of intracellular-membrane transport. N Engl J Med. 2000 Oct 12;343(15):1095-104. PMID: #11027745#
Gibson F, Walsh J, Mburu P, et al. A type VII myosin encoded by the mouse deafness gene shaker-1. Nature 1995;374:62-64.