A scientist is conducting research to discover novel drug targets for antiretroviral agents against HIV. An HIV-positive blood sample is analyzed in the laboratory, and purified CD4 T lymphocytes are extracted. Using molecular tracing techniques, the scientist follows a viral HIV protein that is synthesized in the blood sample's T cells. The protein becomes glycosylated before being proteolytically cleaved into 2 smaller proteins in the Golgi apparatus. Which of the following best describes the function of these 2 newly formed HIV proteins?

Question

A scientist is conducting research to discover novel drug targets for antiretroviral agents against HIV.  An HIV-positive blood sample is analyzed in the laboratory, and purified CD4 T lymphocytes are extracted.  Using molecular tracing techniques, the scientist follows a viral HIV protein that is synthesized in the blood sample's T cells.  The protein becomes glycosylated before being proteolytically cleaved into 2 smaller proteins in the Golgi apparatus.  Which of the following best describes the function of these 2 newly formed HIV proteins?

Quizplus · Accepted Answer

11ec160b_3831_ecd7_9249_cdc74b63aebc_MD0001_00 The HIV genome contains a set of structural genes (gag, pol, and env) that encode polyproteins. These polyproteins are subsequently cleaved by host or viral proteases into the individual proteins that compose the HIV virus. The only glycosylated HIV polyprotein is gp160, the product of the env gene. gp160 is extensively glycosylated in the rough endoplasmic reticulum and Golgi apparatus. It is then cleaved into the envelope proteins gp120, which mediates viral attachment, and gp41, which mediates viral fusion with the host cell. Glycosylation of these proteins is crucial for: (Choices A, B, and C) The pol gene encodes for reverse transcriptase, integrase, and protease, three crucial HIV enzymes. Reverse transcriptase converts single-stranded viral RNA into double-stranded DNA, which is then integrated into the host genome by integrase. Protease helps cleave HIV polyproteins into individual proteins after transcription in the rough endoplasmic reticulum. These enzymes are not glycosylated. (Choice E) Uninfected CD4 cells can undergo activation-induced apoptosis when responding to HIV peptides displayed on the surface of infected cells. CD4 cells infected with HIV are damaged primarily through direct cytopathic effects. Both mechanisms contribute to CD4 cell depletion in HIV infection. Educational objective: In the HIV replication cycle, polyprotein precursors are encoded by the structural genes gag, pol, and env. Only the env gene polyprotein product (gp160) is glycosylated. This polyprotein is subsequently cleaved in the Golgi apparatus to form the envelope glycoproteins gp120 and gp41. __________ References: HIV-1 envelope glycoprotein biosynthesis, trafficking, and incorporation (http://www.ncbi.nlm.nih.gov/pubmed/21762802)

A Scientist Is Conducting Research to Discover Novel Drug Targets