1.A.54.3.3
Signal peptide peptidase, SppL3 of 385 aas and 9 TMSs. Cleaves the single TMS in the neuronal ceroid lipofuscinoses (NCLs), a group of proteins causing recessive disorders of childhood with overlapping symptoms including vision loss, ataxia, cognitive regression and premature death (Jules et al. 2017). CLN5 is implicated in the recruitment of the retromer complex to endosomes, which is required to sort the lysosomal sorting receptors from endosomes to the trans-Golgi network. It is initially translated as a type II transmembrane protein and subsequently cleaved by SPPL3 into a mature soluble protein consisting of residues 93-407 and an N-terminal fragment is then further cleaved by SPPL3 and SPPL2b and degraded in the proteasome (Jules et al. 2017).