Cellular Communication and the Cell Cycle FRQ: a) Low extracellular pH activates TRPV1 through the binding of H + ions to TRPV1. Describe the properties, including the location, of the site of TRPV1 that allow H+ ions to bind. Describe the specific location in the cell where ATF3 protein is produced.

b) The pGoG protein is known to block the G1 to S transition in the cell cycle. Explain why this prevents mitosis from happening in the cell.