Kinesin-like protein KIF3B is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

that in humans is encoded by the ''KIF3B''

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

. KIF3B is an N-type protein that complexes with two other kinesin proteins to form two-headed anterograde motors. First, KIF3B forms a heterodimer with KIF3A ( kinesin-like protein KIF3A); (KIF3A/3B), that is membrane-bound and has

ATPase ATPases (, Adenosine 5'-TriPhosphatase, adenylpyrophosphatase, ATP monophosphatase, triphosphatase, ATP hydrolase, adenosine triphosphatase) are a class of enzymes that catalyze the decomposition of ATP into ADP and a free phosphate ion or ...

activity. Then KIFAP3 (KAP3, kinesin superfamily associated protein–3) binds to the tail domain to form a heterotrimeric motor. This motor has a plus end-directed

microtubule Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nanometer, nm and have an inner diameter bet ...

sliding activity that exhibits a velocity of ~0.3 μm/s a. There are 14 kinesin protein families in the kinesin superfamily and KIF3B is part of the Kinesin-2 family, of kinesins that can all form heterotrimeric complexes. Expression of the three motor subunits is ubiquitous. The KIG3A/3B/KAP3 motors can transport 90 to 160 nm in diameter organelles. There are many orthologous KIF3B genes that are expressed in ''

Drosophila ''Drosophila'' (), from Ancient Greek δρόσος (''drósos''), meaning "dew", and φίλος (''phílos''), meaning "loving", is a genus of fly, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or p ...

'', the

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, '' Bos taurus'', ''

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'', '' Equus caballus'', '' Felis catus'', ''

Macaca mulatta The macaques () constitute a genus (''Macaca'') of sociality, gregarious Old World monkeys of the subfamily Cercopithecinae. The 23 species of macaques inhabit species distribution, ranges throughout Asia, North Africa, and Europe (in Barbary ma ...

'', ''

Mus musculus The house mouse (''Mus musculus'') is a small mammal of the rodent family Muridae, characteristically having a pointed snout, large rounded ears, and a long and almost hairless tail. It is one of the most abundant species of the genus ''Mus (genu ...

'', '' Pan troglodytes'', and ''

Rattus norvegicus ''Rattus'' is a genus of muroid rodents, all typically called rats. However, the term rat can also be applied to rodent species outside of this genus. Species and description The best-known ''Rattus'' species are the black rat (''R. rattus' ...

''.

Function

The heterotrimeric KIF3B/KIF3A/KAP3 motor machinery functions in the intracellular transport of multiple different molecules such as β-catenin and MT1-MMP. KIF3B activity has been implicated with various cellular processes such as intracellular movement of

organelle In cell biology, an organelle is a specialized subunit, usually within a cell (biology), cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as Organ (anatomy), organs are to th ...

intraflagellar transport Intraflagellar transport (IFT) is a bidirectional motility along axoneme microtubules that is essential for the formation (ciliogenesis) and maintenance of most eukaryotic cilia and flagella. It is thought to be required to build all cilia that as ...

, chromosome movement during

mitosis Mitosis () is a part of the cell cycle in eukaryote, eukaryotic cells in which replicated chromosomes are separated into two new Cell nucleus, nuclei. Cell division by mitosis is an equational division which gives rise to genetically identic ...

and

meiosis Meiosis () is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, the sperm or egg cells. It involves two rounds of division that ultimately result in four cells, each with only one c ...

, and cellular interaction with the extracellular matrix. KIF3B also regulates the interaction of cancer cells with the extracellular matrix (ECM), in particular the transport of MT1-MMP to the cancer cell front is essential for collagen fiber matrix realignment and degradation.

Interactions

KIF3B has been shown to interact with the SMC3 subunit of the cohesin complex and with RAB4A.

Function

Interactions

References

Further reading