Question

Monomeric GTPases from the Ras family relay signals from

A. Receptor tyrosine kinases
B. MAP kinases
C. G protein coupled receptors
D. Activated PI 3-kinases
E. AKT

Answer 1

Monomeric GTPases from the Ras family relay signals from receptor tyrosine kinases through G-protein mediated signal transduction. This pathway involves the activation of G proteins, adenylate cyclase, and the production of cAMP. The Ras protein, a member of the Ras family, can activate a phosphorylation cascade leading to the activation of MAP kinase.

Step-by-step explanation:

Monomeric GTPases from the Ras family relay signals from A. Receptor tyrosine kinases.

In G-protein mediated signal transduction, GTP-binding proteins (G-Proteins) transduce extracellular signals by inducing production of second messenger molecules in cells. G-proteins are trimers consisting of alpha, beta, and gamma subunits. When hormones or effector molecules bind to their membrane receptors, an allosteric change occurs on the receptor's cytoplasmic domain, increasing the affinity of the receptor for G proteins on the inner plasma membrane surface. The activated G protein can bind to adenylate cyclase, activating the enzyme and leading to the production of cAMP in the cytosol. This process is an example of G-protein-mediated signal transduction.

The Ras protein, which belongs to the Ras family of GTPases, can activate a phosphorylation cascade leading to the activation of the mitogen-activated protein (MAP) kinase. The Ras gene/protein is involved in many receptor kinase signaling pathways and can promote cell proliferation and differentiation. Mutations in the Ras protein that interfere with its GTPase activity are common in cancer and can lead to uncontrolled cell proliferation.

Answer 2

Monomeric GTPases from the Ras family, such as the RAS protein, primarily relay signals from Receptor Tyrosine Kinases (RTKs) to downstream pathways including the MAP kinase cascade.

Step-by-step explanation:

Monomeric GTPases from the Ras family relay signals from Receptor Tyrosine Kinases (RTKs).

These GTPases are crucial in various cellular processes, including growth, differentiation, and cell survival, by transmitting signals from RTKs to downstream pathways such as the MAP kinase cascade. The RAS protein, a well-known monomeric GTPase, activates the MAP kinase signaling pathway upon GTP binding.

When active, this pathway can influence cellular processes including gene expression and cancer progression. Mutations that impair the GTPase activity of RAS can lead to uncontrolled cell division and are often implicated in the development of cancers.