69. Which of the following statements about membrane proteins are correct?① Membrane proteins can be extracted from cell membrane using sodium dodecyl sulfate.② Integral proteins can span the membrane with α-helical structure or β-sheet structure.③ Estrogen receptor is a membrane protein.④ The membrane proteins are not associated with membrane through glycosylphosphatidylinositol anchor.⑤ The transmembrane helix of membrane proteins can be predicted from hydropathic index of amino acid sequence.
(A) ①②③
(B) ①②⑤
(C) ①②④
(D) ②④⑤
(E) ①③④