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myosin-VIIa (MYO7A USH1B)
Function:
- myosins are actin-based motor molecules with ATPase activity
- unconventional myosins serve in intracellular movements
- their highly divergent tails are presumed to bind to membrane compartments, which would be moved relative to actin filaments
- in retina, myosin 7a might play a role in trafficking of ribbon-synaptic vesicle complexes & renewal of the outer photoreceptors disks
- in inner ear, it might maintain the rigidity of stereocilia during the dynamic movements of the bundle
- involved in hair-cell vesicle trafficking of aminoglycosides, which are known to induce ototoxicity (putative)
- interacts with PLEKHB1 (via PH domain) (putative)
- might homodimerize in a two headed molecule through the formation of a coiled-coil rod
- binds MYRIP & WHRN
Structure:
- contains 2 FERM domains
- contains 5 IQ domains
- contains 1 myosin head-like domain
- contains 2 MyTH4 domains
- contains 1 SH3 domain
Compartment:
- cytoplasm (probable)
- in photoreceptor cells, mainly localized in the inner & base of outer segments as well as in the synaptic ending region
Alternative splicing:
- named isoforms=7
- additional isoforms seem to exist
Expression:
- expressed in the retineal pigment epithelium & in retinal photoreceptor cells
- also found in kidney, liver, testis, cochlea, lymphocytes
- not expressed in brain
- detected in optic cup in 5.5 weeks-old embryos
- expressed in retinal pigment epithelium, cochlear & vestibular neuroepithelia, & olfactory epithelium at 8 weeks
- at 19 weeks, present in both retinal pigment epithelium & retinal photoreceptor cells
- at 24-28 weeks, expression in retinal pigment epithelium & retinal photoreceptor cells increases
- present in retinal pigment epithelium & retinal photoreceptor cells in adult
Pathology:
- defects in MYO7A are the cause of
a) Usher syndrome type 1B
b) deafness autosomal recessive type 2
c) deafness autosomal dominant type 11
Related
MYO7A or USH1B gene
Usher syndrome type 1B/myosin VIIA mutation associated
General
phosphoprotein
unconventional myosin
Properties
SIZE: entity length = 2215 aa
MW = 254 kD
COMPARTMENT: cytoplasm
MOTIF: Myosin head-like {1-729}
MOTIF: ATP-binding site
NAME: ATP-binding site
SITE: 158-165
actin-binding site
SITE: 632-639
FOR-BINDING-OF: F-actin
IQ motif {745-765}
IQ motif {768-788}
IQ motif {791-811}
IQ motif {814-834}
IQ motif {837-857}
coiled coil {858-935}
Ser phosphorylation site {S965}
MyTH4 1 {1017-1253}
FERM 1 {1258-1602}
src homology 3 [SH3] domain
SITE: 1603-1672
MyTH4 2 {1747-1896}
FERM 2 {1902-2205}
Database Correlations
OMIM correlations
MORBIDMAP 276903
UniProt Q13402
PFAM correlations
Entrez Gene 4647
Kegg hsa:4647
References
- UniProt :accession Q13402
- Hereditary hearing loss homepage
http://webhost.ua.ac.be/hhh/
- Mutations of the MYO7A gene
Retina International's Scientific Newsletter
http://www.retina-international.com/sci-news/myomut.htm
- GeneReviews
http://www.ncbi.nlm.nih.gov/sites/genetests/lab/gene/MYO7A