AGBL5 and retinitis pigmentosa 1: Furthermore, human mutations in CCP5 (also known as AGBL5), a tubulin deglutamylase are associated with RP, presumably due to an increase in polyglutamylation (Kastner et al., 2015; Astuti et al., 2016; Branham et al., 2016; Patel et al., 2016).