Biology:Class I PI 3-kinases

Class I PI 3-kinases are a subgroup of the enzyme family, phosphoinositide 3-kinase that possess a common protein domain structure, substrate specificity, and method of activation. Class I PI 3-kinases are further divided into two subclasses, class IA PI 3-kinases and class IB PI 3-kinases.

Class IA PI 3-kinases

Class IA PI 3-kinases are activated by receptor tyrosine kinases (RTKs).

There are three catalytic subunits that are classified as class IA PI 3-kinases:

• p110α
• p110β
• p110δ

There are currently five regulatory subunits that are known to associate with class IA PI 3-kinases catalytic subunits:

• p85α and p85β
• p55α and p55γ
• p50α

Class IB PI 3-kinases

Class IB PI 3-kinases are activated by G-protein-coupled receptors (GPCRs).

The only known class IB PI 3-kinase catalytic subunit is p110γ.

There are two known regulatory subunits for p110γ:

• p101
• p84/ p87PIKAP.

See also

• Phosphoinositide 3-kinase
• Phosphoinositide 3-kinase inhibitor

References

• Stein RC (September 2001). "Prospects for phosphoinositide 3-kinase inhibition as a cancer treatment". Endocr. Relat. Cancer 8 (3): 237–48. doi:10.1677/erc.0.0080237. PMID 11566615. http://erc.endocrinology-journals.org/cgi/reprint/8/3/237. Retrieved 2008-09-24. 
• "The phosphoinositide (PI) 3-kinase family". J. Cell Sci. 116 (Pt 15): 3037–40. August 2003. doi:10.1242/jcs.00609. PMID 12829733. 
• "Signaling by distinct classes of phosphoinositide 3-kinases". Exp. Cell Res. 253 (1): 239–54. November 1999. doi:10.1006/excr.1999.4701. PMID 10579926. http://www.ludwig.ucl.ac.uk/cellsig_pdf/VanhaesebroeckB1999c.pdf.