True about gp. 120 is?
High-Yield Explanation
ANSWER: (A) Virus attachmentREF: Jawetz's 24th ed chapter 44. AIDS & LentivirusesEnvelope glycoprotein GP120 (or gp 120) is a glycoprotein exposed on the surface of the HIV envelope. The 120 in its name comes from its molecular weight of 120 kilodaltons.The SU (gp 120) product of the envgene contains binding domains responsible for virus attachment to the CD4 molecule and coreceptors, determines lymphocyte and macrophage tropisms, and carries the major antigenic determinants that elicit neutralizing antibodies. The gp 120 subunit is on the outside of the cell, and gp 41 is a trans-membrane protein. The TM (gp 41) env product contains both a trans-membrane domain that anchors the glycoprotein in the viral envelope and a fusion domain that facilitates viral penetration into target cells.