KPNA2
Encyclopedia
Importin subunit alpha-2 is a protein
that in humans is encoded by the KPNA2 gene
.
The import of proteins into the nucleus
is a process that involves at least 2 steps. The first is an energy-independent docking
of the protein to the nuclear envelope
and the second is an energy-dependent
translocation through the nuclear pore
complex. Imported proteins require a nuclear localization sequence (NLS) which generally consists of a short region of basic amino acids or 2 such regions spaced about 10 amino acids apart. Proteins involved in the first step of nuclear import are members of the alpha importin
family of karyopherin
s such as importin subunit alpha-2. These include the Xenopus
protein importin and its yeast homolog, SRP1 (a suppressor of certain temperature-sensitive mutations
of RNA polymerase I
in Saccharomyces cerevisiae
), which bind to the NLS. KPNA2 protein interacts with the NLSs of DNA helicase Q1
and SV40 T antigen
and may be involved in the nuclear transport of proteins. KPNA2 also may play a role in V(D)J recombination
with SGK
, PLAG1
, KPNB1
, RECQL
, ARL4A
and ITK
.
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 KPNA2 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...
.
The import of proteins into the nucleus
Cell nucleus
In cell biology, the nucleus is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these...
is a process that involves at least 2 steps. The first is an energy-independent docking
Noncovalent bonding
A noncovalent bond is a type of chemical bond, typically between macromolecules, that does not involve the sharing of pairs of electrons, but rather involves more dispersed variations of electromagnetic interactions. The noncovalent bond is the dominant type of bond between supermolecules in...
of the protein to the nuclear envelope
Nuclear envelope
A nuclear envelope is a double lipid bilayer that encloses the genetic material in eukaryotic cells. The nuclear envelope also serves as the physical barrier, separating the contents of the nucleus from the cytosol...
and the second is an energy-dependent
Ran (biology)
Ran is a small 25Kda protein that is involved in transport into and out of the cell nucleus during interphase and also involved in mitosis. It is a member of the Ras superfamily....
translocation through the nuclear pore
Nuclear pore
Nuclear pores are large protein complexes that cross the nuclear envelope, which is the double membrane surrounding the eukaryotic cell nucleus. There are about on average 2000 nuclear pore complexes in the nuclear envelope of a vertebrate cell, but it varies depending on cell type and the stage in...
complex. Imported proteins require a nuclear localization sequence (NLS) which generally consists of a short region of basic amino acids or 2 such regions spaced about 10 amino acids apart. Proteins involved in the first step of nuclear import are members of the alpha importin
Importin
Importin is a type of protein that moves other protein molecules into the nucleus by binding to a specific recognition sequence, called the nuclear localization signal . Importin is classified as a karyopherin....
family of karyopherin
Karyopherin
Karyopherins are a group of proteins involved in transporting molecules from the cytoplasm into the nucleus of eukaryotic cells. The inside of the nucleus is called the karyoplasm . Generally, karyopherin-mediated transport occurs through the nuclear pore, which acts as a gateway into and out of...
s such as importin subunit alpha-2. These include the Xenopus
African clawed frog
The African clawed frog is a species of South African aquatic frog of the genus Xenopus. Its name is derived from the three short claws on each hind foot, which it uses to tear apart its food...
protein importin and its yeast homolog, SRP1 (a suppressor of certain temperature-sensitive mutations
Permissive temperature
The permissive temperature is the temperature at which a temperature sensitive mutant gene product takes on a normal, functional phenotype.When a temperature sensitive mutant is grown in a permissive condition, the mutated gene product behaves normally , even if there is a mutant allele present...
of RNA polymerase I
RNA polymerase I
RNA polymerase I is, in eukaryotes, the enzyme that only transcribes ribosomal RNA , a type of RNA that accounts for over 50% of the total RNA synthesized in a cell....
in Saccharomyces cerevisiae
Saccharomyces cerevisiae
Saccharomyces cerevisiae is a species of yeast. It is perhaps the most useful yeast, having been instrumental to baking and brewing since ancient times. It is believed that it was originally isolated from the skin of grapes...
), which bind to the NLS. KPNA2 protein interacts with the NLSs of DNA helicase Q1
RECQL
ATP-dependent DNA helicase Q1 is an enzyme that in humans is encoded by the RECQL gene.-Interactions:RECQL has been shown to interact with KPNA4 and Karyopherin alpha 2.-Further reading:...
and SV40 T antigen
SV40 Large T-antigen
SV40 large T antigen is a hexamer protein that is a proto-oncogene derived from the polyomavirus SV40 which is capable of transforming a variety of cell types. The transforming activity of TAg is due in large part to its perturbation of the retinoblastoma and p53 tumor suppressor proteins...
and may be involved in the nuclear transport of proteins. KPNA2 also may play a role in V(D)J recombination
V(D)J recombination
VJ recombination, also known as somatic recombination, is a mechanism of genetic recombination in the early stages of immunoglobulin and T cell receptors production of the immune system...
Interactions
Karyopherin alpha 2 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 SGK
SGK
Serine/threonine-protein kinase SGK is a kinase subfamily that is currently known as being encoded by SGK1, SGK2, and SGK3 genes.The SGK1 kinase regulates the myo-inositol transporter during osmotic stress....
, PLAG1
PLAG1
Zinc finger protein PLAG1 is a protein that in humans is encoded by the PLAG1 gene.-Interactions:PLAG1 has been shown to interact with Karyopherin alpha 2.- External links :...
, KPNB1
KPNB1
Importin subunit beta-1 is a protein that in humans is encoded by the KPNB1 gene.-Interactions:KPNB1 has been shown to interact with NUP98, Karyopherin alpha 1, KPNA3, Karyopherin alpha 2, SMN1, Parathyroid hormone-related protein, Nucleoporin 62, RANBP2, Ran , RANBP1, NUP50, P53, NUP153 and...
, RECQL
RECQL
ATP-dependent DNA helicase Q1 is an enzyme that in humans is encoded by the RECQL gene.-Interactions:RECQL has been shown to interact with KPNA4 and Karyopherin alpha 2.-Further reading:...
, ARL4A
ARL4A
ADP-ribosylation factor-like protein 4A is a protein that in humans is encoded by the ARL4A gene.-Interactions:ARL4A has been shown to interact with Karyopherin alpha 2.-Further reading:...
and ITK
ITK (gene)
IL2-inducible T-cell kinase, also known as ITK, is a protein that in humans is encoded by the ITK gene.- Function :This gene encodes an intracellular tyrosine kinase expressed in T-cells...
.