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Aliases KIFAP3, FLA3, KAP-1, KAP-3, KAP3, SMAP, Smg-GDS, dJ190I16.1, kinesin associated protein 3
External IDs MGI: 107566 HomoloGene: 7799 GeneCards: 22920
Genetically Related Diseases
Disease Name References
amyotrophic lateral sclerosis
RNA expression pattern
PBB GE KIFAP3 203333 at tn.png
More reference expression data
Species Human Mouse
RefSeq (mRNA)



RefSeq (protein)



Location (UCSC) Chr 1: 169.92 – 170.09 Mb Chr 1: 163.78 – 163.92 Mb
PubMed search [2] [3]
View/Edit Human View/Edit Mouse

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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