Figure 4. Specific TSG101 domains are required for p21 promoter binding and repression.

(A) Left, TSG101 contains 391 amino acids with the four indicated domains. Constructs expressing myc-tagged full-length or truncated forms of TSG101 are illustrated. Right, p21 promoter binding and repression by these TSG101 variants are summarized. ND, not determined. (B) Binding of full-length TSG101 and its truncated forms to the p21 promoter was examined by chromatin immunoprecipitation. DNA fragments, which co-precipitated with anti-myc antibody, were PCR-amplified using the primer set “d”, as shown in Figure 3A. Expression of TSG101 variants is shown by the Western blot in the bottom panel. Asterisk indicates the position of non-specific bands. (C) p21 promoter activity was assessed in Saos-2-2 cells expressing different forms of TSG101. Empty vector sample was included as control, and its promoter activity was set as 1. Data presented are the average of five independent experiments (*P<0.05, Student's t test).