Figure 3.

Ubiquilin-1 transcript variants (TV). The full-length ubiquilin-1 TV1 is encoded by 11 exons. Ubiquilin-1 has two signature domains of ubiquitin-like proteins: The N-terminal UBL (ubiquitin-like) domain (orange) and the C-terminal UBA (ubiquitin-associated) domain (green). UBA binds to polyubiquitinated proteins and UBL mediates interaction with the proteasome. The central region consists of conserved asparagine- and proline-rich repeats that mediate ubiquilin-1 interaction with other proteins. TV2 lacks exon 8 (light blue). TV3 lacks exons 2, 3, and 4 and therefore has an incomplete UBL domain. TV4 contains the first 3 exons and a unique short C-terminus (grey) due to a frame shift leading to a 32-amino acid insertion after the exon 3/5 junction.