UBB+1 is shorthand for Ubiquitin-B+1, a frameshifted mutant arising from the Ubiquitin B gene.
UBB+1 can be truncated by yeast ubiquitin hydrolase 1 (YUH1) and ubiquitin C-terminal hydrolase L3 UCHL3 despite of the fact that the glycine at position 76 as been substituted for a tyrosine.