Which statements describe the structure of the pyruvate dehydrogenase (PDH) complex? (could be more than one)
1) The complex contains multiple copies of each of three enzymes.
2) The core of the complex is made up of several copies of E1.
3) A regulatory kinase and phosphatase are part of the PDH complex.
4) Several copies each of E1 and E3 surround E2.
5) E2 contains three domains.