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	'''Protein ~~kinase~~ B''' (~~'''~~PKB~~'''~~), also known as '''Akt''', is a serine/threonine-specific protein kinase that plays a key role in multiple cellular processes such as glucose metabolism, apoptosis, cell proliferation, transcription and cell migration.		== Protein Kinase B ==

			[[File:Signal_transduction_pathways.svg\|thumb\|right\|Diagram of signal transduction pathways including Protein Kinase B]]

			'''Protein Kinase B''' (PKB), also known as '''Akt''', is a serine/threonine-specific protein kinase that plays a key role in multiple cellular processes such as glucose metabolism, apoptosis, cell proliferation, transcription, and cell migration. PKB is a central node in the [[PI3K/AKT/mTOR pathway]], which is critical for cell survival and growth.

	== Structure ==		== Structure ==
	~~PKB is a 57 kDa protein that is activated by insulin, growth factors and other signaling molecules. It~~ is composed of three isoforms: ~~PKBα (~~Akt1), ~~PKBβ (~~Akt2) and ~~PKBγ (~~Akt3). ~~Each isoform has~~ a similar structure, ~~but they have different expression patterns~~ and ~~functions~~.
			Protein Kinase B is composed of three isoforms: Akt1, Akt2, and Akt3, each encoded by separate genes. These isoforms share a similar structure, consisting of an N-terminal pleckstrin homology (PH) domain, a central kinase domain, and a C-terminal regulatory domain. The PH domain is responsible for binding to phosphoinositides, which localizes PKB to the plasma membrane where it is activated.

			== Activation ==

			PKB is activated through a series of phosphorylation events. The activation process begins with the binding of growth factors to receptor tyrosine kinases, leading to the activation of [[phosphoinositide 3-kinase]] (PI3K). PI3K catalyzes the production of phosphatidylinositol (3,4,5)-trisphosphate (PIP3), which recruits PKB to the membrane via its PH domain. Once at the membrane, PKB is phosphorylated at two key residues: Thr308 in the activation loop and Ser473 in the hydrophobic motif, by [[PDK1]] and [[mTORC2]], respectively.

	== Function ==		== Function ==
	PKB is involved in the regulation of glucose metabolism by promoting the translocation of the glucose transporter GLUT4 to the cell membrane. It also inhibits apoptosis by phosphorylating and inactivating several targets, including Bad, forkhead transcription factors and caspase-9. In addition, PKB promotes cell proliferation by activating the mTOR pathway and inhibiting the GSK3β pathway.

	== ~~Role in disease~~ ==		PKB regulates a variety of cellular processes:
	~~Abnormal activation~~ of PKB ~~has been~~ implicated in ~~several~~ diseases, including cancer, diabetes, and cardiovascular ~~disease~~. ~~In cancer~~, ~~PKB promotes cell survival and~~ growth, and ~~its activation is often associated with~~ resistance to ~~chemotherapy~~. In diabetes, impaired PKB signaling can lead to insulin resistance and hyperglycemia. In cardiovascular disease, PKB has a protective role by promoting angiogenesis and preventing apoptosis of cardiac cells.
			* '''Glucose Metabolism''': PKB promotes glucose uptake by facilitating the translocation of [[GLUT4]] to the cell membrane and enhances glycolysis by phosphorylating and activating key enzymes.
			* '''Cell Survival''': PKB inhibits apoptosis by phosphorylating and inactivating components of the apoptotic machinery, such as [[BAD]] and [[caspase-9]].
			* '''Cell Growth and Proliferation''': PKB stimulates cell growth by activating the mTOR pathway and promotes cell cycle progression by phosphorylating and inhibiting cell cycle inhibitors like [[p21]] and [[p27]].

			== Clinical Significance ==

			Dysregulation of PKB signaling is implicated in various diseases, including cancer, diabetes, and cardiovascular diseases. Overactivation of PKB is commonly observed in cancers, where it contributes to tumor growth and resistance to apoptosis. Inhibitors targeting the PI3K/AKT/mTOR pathway are being developed as potential therapeutic agents for cancer treatment.

			== Related Pages ==

	~~== See also ==~~		* [[Signal transduction]]
	* [[~~Protein~~ kinase]]		* [[Phosphoinositide 3-kinase]]
	* [[~~Insulin~~]]		* [[mTOR]]
	* [[Apoptosis]]		* [[Apoptosis]]
	* [[Cell proliferation]]
	* [[Cancer]]		* [[Cancer]]
	* [[Diabetes]]
	* [[Cardiovascular disease]]

	~~== References ==~~		{{Signal transduction}}
	~~<references />~~

	[[Category:Protein kinases]]		[[Category:Protein kinases]]
	[[Category:~~Cell biology~~]]		[[Category:Signal transduction]]
	~~[[Category:Molecular biology]]~~
	~~[[Category:Biochemistry]]~~
	~~{{stub}}~~
	~~{{dictionary-stub1}}~~

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'''Protein kinase B''' ('''PKB'''), also known as '''Akt''', is a serine/threonine-specific protein kinase that plays a key role in multiple cellular processes such as glucose metabolism, apoptosis, cell proliferation, transcription and cell migration.

== Structure ==
PKB is a 57 kDa protein that is activated by insulin, growth factors and other signaling molecules. It is composed of three isoforms: PKBα (Akt1), PKBβ (Akt2) and PKBγ (Akt3). Each isoform has a similar structure, but they have different expression patterns and functions.

== Function ==
PKB is involved in the regulation of glucose metabolism by promoting the translocation of the glucose transporter GLUT4 to the cell membrane. It also inhibits apoptosis by phosphorylating and inactivating several targets, including Bad, forkhead transcription factors and caspase-9. In addition, PKB promotes cell proliferation by activating the mTOR pathway and inhibiting the GSK3β pathway.

== Role in disease ==
Abnormal activation of PKB has been implicated in several diseases, including cancer, diabetes, and cardiovascular disease. In cancer, PKB promotes cell survival and growth, and its activation is often associated with resistance to chemotherapy. In diabetes, impaired PKB signaling can lead to insulin resistance and hyperglycemia. In cardiovascular disease, PKB has a protective role by promoting angiogenesis and preventing apoptosis of cardiac cells.

== See also ==
* [[Protein kinase]]
* [[Insulin]]
* [[Apoptosis]]
* [[Cell proliferation]]
* [[Cancer]]
* [[Diabetes]]
* [[Cardiovascular disease]]

== References ==
<references />

[[Category:Protein kinases]]
[[Category:Cell biology]]
[[Category:Molecular biology]]
[[Category:Biochemistry]]
{{stub}}
{{dictionary-stub1}}

Protein kinase B - Revision history

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