KIFAP3
Encyclopedia
Kinesin-associated protein 3 is a protein
that in humans is encoded by the KIFAP3 (also known as KAP3) gene
. It is a non-motor, accesssory 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.
) is a regulator protein having two activities on a group of small G protein
s 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 , 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.
with , and .
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
that in humans is encoded by the KIFAP3 (also known as KAP3) gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
. It is a non-motor, accesssory 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.
Function
The small G protein GDP dissociation stimulator (smg GDSRAP1GDS1
Rap1 GTPase-GDP dissociation stimulator 1 is an enzyme that in humans is encoded by the RAP1GDS1 gene.-Interactions:RAP1GDS1 has been shown to interact with KIFAP3, HRAS and RHOA.-Further reading:...
) is a regulator protein having two activities on a group of small G protein
Small GTPase
Small GTPases are a family of hydrolase enzymes that can bind and hydrolyze guanosine triphosphate . They are a form of G-proteins found in the cytosol which are homologous to the alpha subunit of heterotrimeric G-proteins, but unlike the alpha subunit of G proteins, a small GTPase can function...
s including the Rho
Rho family of GTPases
The Rho family of GTPases is a family of small signaling G protein , and is a subfamily of the Ras superfamily. The members of the Rho GTPase family have been shown to regulate many aspects of intracellular actin dynamics, and are found in all eukaryotic organisms including yeasts and some plants...
and Rap1
Rap1
Rap1 is a small GTPase, which are small cytosolic proteins that act like cellular switches and are vital for effective signal transduction. There are two isoforms of the Rap1 protein, each encoded by a separate gene, RAP1A and RAP1B...
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
Armadillo repeats
Armadillo repeats are named after the β-catenin-like Armadillo protein of the fruit fly Drosophila. These repeats are about 40 amino acids long and proteins that contain them have many tandemly repeated copies. Each Armadillo repeat is composed of a pair of alpha helices that form a hairpin...
and interacts with the smg GDS protein through these repeats. This protein, which is highly concentrated around the endoplasmic reticulum
Endoplasmic reticulum
The endoplasmic reticulum is an organelle of cells in eukaryotic organisms that forms an interconnected network of tubules, vesicles, and cisternae...
, is phosphorylated
Phosphorylation
Phosphorylation is the addition of a phosphate group to a protein or other organic molecule. Phosphorylation activates or deactivates many protein enzymes....
by , 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
SMC2
Structural maintenance of chromosomes protein 2 also known as chromosome-associated protein E is a protein that in humans is encoded by the SMC2 gene....
) and KIF3A/B, a kinesin
Kinesin
A kinesin is a protein belonging to a class of motor proteins found in eukaryotic cells. Kinesins move along microtubule filaments, and are powered by the hydrolysis of ATP . The active movement of kinesins supports several cellular functions including mitosis, meiosis and transport of cellular...
superfamily protein in the nucleus, and that it plays a role in the interaction of chromosomes with an ATPase motor protein.
Interactions
KIFAP3 has been shown to interactProtein-protein interaction
Protein–protein interactions occur when two or more proteins bind together, often to carry out their biological function. Many of the most important molecular processes in the cell such as DNA replication are carried out by large molecular machines that are built from a large number of protein...
with , and .