複選題7.Which of the following descriptions of G-protein-coupled receptors (GPCRs)CORRECT?(A) GPCRs are a-helical transmembrane proteins.(B) GPCRs have intrinsic GTPase activity.(C) Activated GPCRs can activate 10-100 Ga proteins.(D) Activated GPCRs increase GDP release from Ga(E) GPCRs are desensitized by phosphorylation.