Question

True facts about Ras and Galfa Ras and G alfa Subunits belong to the GTPase Superfamily Activation of both Ras and G a is triggered by transcription activation of RFS Activation of both Ras and Ga is triggered by hormone binding to an appropriate cell surface receptor Ras activation is accelerated by a protein called guanine nucleotide exchange factor Ras activation is accelerated by a protein called gap binding protein

Answer 1

Ans.

1.

• Both Ras and G alpha subunits belong to the GTPase superfamily.
• Ras is a group of related proteins expressing in all cells and organs whereas G alpha is a subunit of heterotrimeric G protein which stimulates the cAMP dependent pathway through the activation of adenylyl cyclase and works as cellular signaling protein.

2.

• Both Ras and G alpha subunit stay in two mode "On" and "of" depending upon the signaling molecule.
• Both are not activated RFS transcription activation.

3.

• Both belong to a GPCR family which is activated upon the binding of a signaling molecule to the cell surface receptor.
• Signaling molecule may be a hormone, a drug... etc.

4.

• Ras is a guanosine - nucleotide binding protein. In the "of" state it is bound to the GDP where as in the "on" state it is bound to the GTP molecule.

5.

• Ras is inactivated by the GTPase activating protein (GAP) through activation of GTPase activity.
• So, GAP functions as a RAS inhibitor.