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Kinesin-associated protein 3
Symbols KIFAP3 ; FLA3; KAP-1; KAP-3; KAP3; SMAP; Smg-GDS; dJ190I16.1
External IDs OMIM601836 MGI107566 HomoloGene7799 GeneCards: KIFAP3 Gene
RNA expression pattern
PBB GE KIFAP3 203333 at tn.png
More reference expression data
Species Human Mouse
Entrez 22920 16579
Ensembl ENSG00000075945 ENSMUSG00000026585
UniProt Q92845 P70188
RefSeq (mRNA) NM_001204514 NM_010629
RefSeq (protein) NP_001191443 NP_034759
Location (UCSC) Chr 1:
169.89 – 170.05 Mb
Chr 1:
163.78 – 163.92 Mb
PubMed search [1] [2]

Kinesin-associated protein 3 is a protein that in humans is encoded by the KIFAP3 (also known as KAP3) gene.[1][2] It is a non-motor, accessory subunit which co-oligomerizes with the motor subunits KIF3A and KIF3B or KIF3C, to form heterotrimeric kinesin-2 motor proteins. Kinesin-2 KAP subunits were initially characterized in echinoderms and mice.[3][4]


The small G protein GDP dissociation stimulator (smg GDS) is a regulator protein having two activities on a group of small G proteins including the Rho and Rap1 family members and Ki-Ras; one is to stimulate their GDP/GTP exchange reactions, and the other is to inhibit their interactions with membranes. The protein encoded by this gene contains 9 Armadillo repeats and interacts with the smg GDS protein through these repeats. This protein, which is highly concentrated around the endoplasmic reticulum, is phosphorylated by v-src , and this phosphorylation reduces the affinity of the protein for smg GDS. It is thought that this protein serves as a linker between human chromosome-associated polypeptide (HCAP) and KIF3A/B, a kinesin superfamily protein in the nucleus, and that it plays a role in the interaction of chromosomes with an ATPase motor protein.[2]


KIFAP3 has been shown to interact with APC ,[5] SMC3 [6] and RAP1GDS1 .[1]


  1. ^ a b Shimizu K, Kawabe H, Minami S, Honda T, Takaishi K, Shirataki H, Takai Y (Dec 1996). "SMAP, an Smg GDS-associating protein having arm repeats and phosphorylated by Src tyrosine kinase". J Biol Chem 271 (43): 27013–7. doi:10.1074/jbc.271.43.27013. PMID 8900189. 
  2. ^ a b "Entrez Gene: KIFAP3 kinesin-associated protein 3". 
  3. ^ Wedaman KP, Meyer DW, Rashid DJ, Cole DG, Scholey JM (February 1996). "Sequence and submolecular localization of the 115-kD accessory subunit of the heterotrimeric kinesin-II (KRP85/95) complex". J. Cell Biol. 132 (3): 371–80. doi:10.1083/jcb.132.3.371. PMC 2120715. PMID 8636215. 
  4. ^ Yamazaki H, Nakata T, Okada Y, Hirokawa N (August 1996). "Cloning and characterization of KAP3: a novel kinesin superfamily-associated protein of KIF3A/3B". Proc. Natl. Acad. Sci. U.S.A. 93 (16): 8443–8. doi:10.1073/pnas.93.16.8443. PMC 38690. PMID 8710890. 
  5. ^ Jimbo T, Kawasaki Y, Koyama R, Sato R, Takada S, Haraguchi K, Akiyama T (April 2002). "Identification of a link between the tumour suppressor APC and the kinesin superfamily". Nat. Cell Biol. 4 (4): 323–7. doi:10.1038/ncb779. PMID 11912492. 
  6. ^ Shimizu K, Shirataki H, Honda T, Minami S, Takai Y (March 1998). "Complex formation of SMAP/KAP3, a KIF3A/B ATPase motor-associated protein, with a human chromosome-associated polypeptide". J. Biol. Chem. 273 (12): 6591–4. doi:10.1074/jbc.273.12.6591. PMID 9506951. 

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