FIG. 4.

ASB3 recruits Elongin-C. (A) Alignment of SOCS boxes of ASB family members and SOCS family members from the human genome database. CE-ASB is a putative ASB identified from the Caenorhabilitis elegans genome database (accession no. U39995). The α-helices (cyan shading) and β-strands (yellow shading) were predicted with the 3D-PSSM web tool, version 2.5.6 (http://www.sbg.bio.ic.ac.uk/∼3dpssm/). Tyrosine residues of α4-helix, the leucine and cysteine residues responsible for the Elongin-C (14) interaction, and the two conserved arginine residues of the α2-helix are shown with red letters. (B) 293 cells were cotransfected with ASB3 or SOCS-1 and Elongin-C and Elongin-B. Whole-cell extracts were prepared for immunoprecipitation with control IgG or anti-c-Myc, followed by Western blot analysis with anti-Elongin-C (top) or anti-c-Myc (middle). The bottom panel shows the expression of Elongin-C.