MYO7A

v

Myosin VIIA
Identifiers
Symbols	MYO7A ; DFNA11; DFNB2; MYOVIIA; MYU7A; NSRD2; USH1B
External IDs	OMIM: 276903 MGI: 104510 HomoloGene: 219 GeneCards: MYO7A Gene
Gene ontology Molecular function • microfilament motor activity • protein binding • calmodulin binding • ATP binding • protein domain specific binding • spectrin binding • actin-dependent ATPase activity • protein homodimerization activity • ADP binding • protein N-terminus binding • actin filament binding Cellular component • photoreceptor outer segment • photoreceptor inner segment • cytoplasm • lysosomal membrane • cytosol • cell cortex • apical plasma membrane • myosin VII complex • photoreceptor connecting cilium • stereocilium • melanosome • synapse • upper tip-link density Biological process • phagolysosome assembly • intracellular protein transport • lysosome organization • visual perception • sensory perception of sound • metabolic process • actin filament-based movement • eye photoreceptor cell development • post-embryonic organ morphogenesis • sensory perception of light stimulus • equilibrioception • pigment granule transport • auditory receptor cell stereocilium organization Sources: Amigo / QuickGO
Orthologs
Species	Human	Mouse
Entrez	4647	17921
Ensembl	ENSG00000137474	ENSMUSG00000030761
UniProt	Q13402	P97479
RefSeq (mRNA)	NM_000260	NM_001256081
RefSeq (protein)	NP_000251	NP_001243010
Location (UCSC)	Chr 11: 77.13 – 77.22 Mb	Chr 7: 98.05 – 98.12 Mb
PubMed search	[1]	[2]

Myosin VIIA is protein that in humans is encoded by the MYO7A gene. Myosin VIIA is a member of the unconventional myosin superfamily of proteins. Myosins are actin binding molecular motors that use the enzymatic conversion of ATP - ADP + inorganic phosphate (Pi) to provide the energy for movement.

Myosins are mechanochemical proteins characterized by the presence of a motor domain, an actin-binding domain, a neck domain that interacts with other proteins, and a tail domain that serves as an anchor. Myosin VIIA is an unconventional myosin with a very short tail. Unconventional myosins have diverse functions in eukaryotic cells and are primarily thought to be involved in the movement or linkage of intra-cellular membranes and organelles to the actin cytoskeleton via interactions mediated by their highly divergent tail domains.

MYO7A is expressed in a number of mammalian tissues, including testis, kidney, lung, inner ear, retina and the ciliated epithelium of the nasal mucosa.

Clinical significance

Mutations in the MYO7A gene cause the Usher syndrome type 1B, a combined deafness/blindness disorder. Affected individuals are typically profoundly deaf at birth and then undergo progressive retinal degeneration.

Model organisms

Myo7a mutant mouse phenotype

Characteristic	Phenotype
Homozygote viability	Normal
Fertility	Normal
Body weight	Abnormal
Anxiety	Normal
Neurological assessment	Abnormal
Grip strength	Abnormal
Hot plate	Abnormal
Dysmorphology	Normal
Indirect calorimetry	Abnormal
Glucose tolerance test	Abnormal
Auditory brainstem response	Abnormal
DEXA	Abnormal
Radiography	Abnormal
Body temperature	Normal
Eye morphology	Normal
Clinical chemistry	Abnormal
Plasma immunoglobulins	Normal
Haematology	Normal
Peripheral blood lymphocytes	Normal
Micronucleus test	Normal
Heart weight	Normal
Tail epidermis wholemount	Normal
Skin Histopathology	Normal
All tests and analysis from

Model organisms have been used in the study of MYO7A function. A spontaneous mutant mouse line, called Myo7a^sh1-6J was generated. Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion. Twenty three tests were carried out on mutant mice and ten significant abnormalities were observed. Male homozygous mutant mice displayed a decreased body weight, a decrease in body fat, improved glucose tolerance and abnormal pelvic girdle bone morphology. Homozygous mutant mice of both sex displayed various abnormalities in a modified SHIRPA test, including abnormal gait, tail dragging and an absence of pinna reflex, a decrease in grip strength, an increased thermal pain threshold, severe hearing impairment and a number of abnormal indirect calorimetry and clinical chemistry parameters.

External links

• GeneReviews/NCBI/NIH/UW entry on Usher Syndrome Type I