formin-binding protein 1 (formin-binding protein 17, hFBP17, FNBP1, FBP17, KIAA0554)

Function

• link between RND2 signaling & regulation of actin cytoskeleton
• coordinates membrane tubulation with reorganization of actin cytoskeleton during endocytosis
• binds to lipids, i.e. phosphatidylinositol 4,5-bisphosphate & phosphatidylserine & promotes membrane invagination & formation of tubules
• enhances actin polymerization via the recruitment of WASL/N-WASP, which in turn activates the Arp2/3 complex
• actin polymerization may promote fission of membrane tubules to form endocytic vesicles
• required for the lysosomal retention of FASLG/FASL
• interacts specifically with GTP-bound RND2 & CDC42
• interacts with PDE6G & microtubules (putative)
• self-associates & can polymerize to form filamentous structures
• interacts with AKAP9, ARHGAP17, DAAM1, DIAPH1, DIAPH2, DNM1, DNM2, DNM3, FASLG/FASL, SNX2 & WASL/N-WASP
• may interact with TNK

Structure

• belongs to the FNBP1 family.
• contains 1 FCH domain.
• contains 1 REM repeat (Hr1 repeat)
• contains 1 SH3 domain

Compartment

• cytoplasm
• enriched in cortical regions coincident with F-actin
• localizes to endocytic vesicles & lysosomes

Alternative splicing

named isoforms=4

Expression

• expressed in epithelial cells of GI tract, respiratory, reproductive & urinary systems
• expressed in brown adipose tissue, cardiomyocytes, enteric ganglia, glucagon producing cells of pancreas
• expressed in germ cells of testis
• expressed in all regions of the brain

Pathology

• a chromosomal translocation t(9;11)(q34;q23) involving FNBP1 with MLL is found in acute leukemias
• low incidence of MLL-FNBP1 fusion protein in acute leukemia may reflect marginal capacity of this fusion protein to induce cellular transformation

More general terms

• cytoskeletal protein
• phosphoprotein
• formin binding protein

Database

• OMIM: https://mirror.omim.org/entry/606191
• UniProt: http://www.uniprot.org/uniprot/Q96RU3.html