Phosphatidylinositol 3-kinase regulatory subunit alpha is an
enzyme
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...
that in humans is encoded by the ''PIK3R1''
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 ...
.
Function
Phosphatidylinositol 3-kinase phosphorylates the
inositol ring of
phosphatidylinositol at the 3-prime position. The enzyme comprises a 110 kD catalytic subunit and a regulatory subunit of either 85, 55, or 50 kD. The ''Pik3r1'' gene locus encodes the 85 kD regulatory subunit, as well as 55 and 50 kD regulatory subunits. It used to be thought that alternative splicing of this gene resulted in three transcript variants encoding different isoforms. In fact, it has since been shown that the 55 and 50kD subunits have their own promotors within the gene locus ''Pik3r1''.
Phosphatidylinositol 3-kinase plays an important role in the metabolic actions of
insulin
Insulin (, from Latin ''insula'', 'island') is a peptide hormone produced by beta cells of the pancreatic islets encoded in humans by the insulin (''INS)'' gene. It is the main Anabolism, anabolic hormone of the body. It regulates the metabol ...
, and a mutation in this gene has been associated with
insulin resistance. Suppression specifically of the 85kD subunit in early murine embryoid body development results in a transient cell-cell adhesion deficiency, mediated by transient downregulation of the adhesion molecule integrin-beta1 (ITGB1).
[
]
Clinical significance
Mutations in ''PIK3R1'' are implicated in cases of breast cancer
Breast cancer is a cancer that develops from breast tissue. Signs of breast cancer may include a Breast lump, lump in the breast, a change in breast shape, dimpling of the skin, Milk-rejection sign, milk rejection, fluid coming from the nipp ...
.SHORT syndrome
SHORT syndrome is an uncommon autosomal-dominant condition marked by ocular depression, Rieger anomaly, teething delay, small height, hyperextensibility of joints, and/or hernias. It was characterized in 1975.
Signs and symptoms
The acronym SHO ...
.
Interactions
PIK3R1 has been shown to interact with:
* ADAM12,CD28
CD28 (Cluster of Differentiation 28) is a protein expressed on T cells that provides essential co-stimulation, co-stimulatory signals required for T cell activation and survival. When T cells are stimulated through CD28 in conjunction with the T- ...
,ERBB3
Receptor tyrosine-protein kinase erbB-3, also known as HER3 (human epidermal growth factor receptor 3), is a membrane bound protein that in humans is encoded by the ''ERBB3'' gene.
ErbB3 is a member of the EGFR family, epidermal growth factor re ...
,Grb2
Growth factor receptor-bound protein 2, also known as Grb2, is an adaptor protein involved in signal transduction/ cell communication. In humans, the GRB2 protein is encoded by the ''GRB2'' gene.
The protein encoded by this gene binds recepto ...
,VAV1
Proto-oncogene vav is a protein that in humans is encoded by the ''VAV1'' gene.
Function
The protein encoded by this proto-oncogene is a member of the Dbl family of guanine nucleotide exchange factors (GEF) for the Rho family of GTP binding ...
,[ and
* WAS.]
References
Further reading
*
*
*
*
*
*
*
{{PDB Gallery, geneid=5295