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Betaherpesvirus UL82/83 protein N terminus This family represents the N terminal region of the Betaherpesvirus UL82 and UL83 proteins. As viruses are reliant upon their host cell to serve as proper environments for their replication, many have evolved mechanisms to alter intracellular conditions to suit their own needs. Human cytomegalovirus induces quiescent cells to enter the cell cycle and then arrests them in late G(1), before they enter the S phase, a cell cycle compartment that is presumably favourable for viral replication. The protein product of the human cytomegalovirus UL82 gene, pp71, can accelerate the movement of cells through the G(1) phase of the cell cycle. This activity would help infected cells reach the late G(1) arrest point sooner and thus may stimulate the infectious cycle. pp71 also induces DNA synthesis in quiescent cells, but a pp71 mutant protein that is unable to induce quiescent cells to enter the cell cycle still retains the ability to accelerate the G(1) phase. Thus, the mechanism through which pp71 accelerates G(1) cell cycle progression appears to be distinct from the one that it employs to induce quiescent cells to exit G(0) and subsequently enter the S phase.
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