Functionally, G Proteins Are Classified into What Three Types

Functionally, G proteins are classified into what three types?

A) those that affect ion channels, stimulatory G proteins, and inhibitory G proteins
B) first, second, and third messengers
C) slow, fast, and opened or closed
D) alpha, beta, and gamma
E) those that affect proteins, those that affect enzymes, and those that affect specific genes