Oncogenes part II

PI3K (Phosphatidylinositol 3

kinase)

PIP2 (Phosphatidylinositol (4,5) bisphosphate)

A lipid molecule in the plasma membrane that is the substrate for PI3K.

PIP3 (Phosphatidylinositol (3,4,5) triphosphate)

The product of PI3K converting PIP2 by adding a phosphate group, which attracts different proteins to the membrane.

PI3K structure

Consists of a 110 kD catalytic subunit and an 85 kD regulatory subunit.

PTEN (Phosphatase and Tensin homolog)

A phosphatase that acts as an "off" switch for the PI3K signaling pathway by converting PIP3 back to PIP2.

AKT (protein kinase B)

A serine/threonine kinase that is recruited by PIP3 to the membrane and is considered the most consequential immediate effect of PI3K signaling.

How loss of PTEN function contributes to cancer

It results in higher PIP3 levels and constitutive activation of AKT, which promotes changes in cell growth, proliferation, and survival.

Myc

A transcription factor with a basic helix

Burkitt's lymphoma

A B

Myc::Max

The heterodimer formed by Myc binding to the highly related protein Max, which binds to DNA and activates the transcription of other genes.

How Myc promotes division

It activates the expression of cell cycle proteins like cyclin D2 and cdk4, and represses the expression of the Cdk inhibitor p21.

Chronic Myelogenous Leukemia (CML)

A type of leukemia characterized by the uncontrolled overproduction of myeloid cells.

BCR

ABL fusion protein