myosin-9b; unconventional myosin-9b (MYO9B, MYR5)

Function

• myosins are actin-based motor molecules with ATPase activity
• unconventional myosins serve in intracellular movements
• may be involved in the remodeling of the actin cytoskeleton
• binds actin with high affinity both in the absence & presence of ATP & its mechanochemical activity is inhibited by Ca+2
• acts as a GTPase activator for RhoA
  • role in the regulation of cell migration via interaction with SLIT2 receptor ROBO1
  • interaction with ROBO1 impairs interaction with RHOA & subsequent activation of RHOA GTPase activity, thus increasing levels of active, GTP-bound RHOA
• interacts (via IQ domains) with CALM

Structure

• belongs to the TRAFAC class myosin-kinesin ATPase superfamily, myosin family
• contains 4 IQ domains
• contains 1 myosin head-like domain
• contains 1 phorbol-ester/DAG-type Zn+2 finger
• contains 1 Ras-associating domain
• contains 1 Rho-GAP domain

Compartment

• cytoplasm, cell cortex, perinuclear region, cytoskeleton
• in undifferentiated cells, colocalizes with F-actin in the cell periphery
• in differentiated cells, its localization is cytoplasmic with the highest levels in the perinuclear region

Alternative splicing

named isoforms=2; long, short

Expression

• expressed predominantly in peripheral blood leukocytes
• expressed at lower levels, in thymus, spleen, testis, prostate, ovary, brain, small intestine & lung

Pathology

• genetic variation in MYO9B is the cause of susceptibility to celiac disease type 4

More general terms

• unconventional myosin
• zinc finger protein
• phosphoprotein
• human longevity protein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=4650
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:4650
• OMIM: https://mirror.omim.org/entry/602129
• OMIM: https://mirror.omim.org/entry/609753
• UniProt: http://www.uniprot.org/uniprot/Q13459.html