| Modification Notes |
The LASS (longevity assurance homolog) family members are highly conserved from yeasts to mammals. Six members of this family of proteins have been characterized (LASS1, LASS2, LASS3, LASS4, LASS5 and LASS6) and they are all involved in sphingolipid synthesis. LASS5, also called TRH4, is a 392 amino acid endoplasmic reticulum, multi-pass membrane protein. On the luminal side of the endoplasmic reticulum membrane, the N-terminal asparagine residue is glycosylated. Functioning as a bona fide (dihydro)ceramide synthase, LASS5 increases the levels of short ceramide species, such as C14:0- and C16:0-ceramides as well as those selectively enriched in palmitic acid. LASS5 is the most abundantly expressed longevity assurance homolog in lung epithelia where it functions as a regulator of PtdCho metabolism. In cells deficient for CLN9, as observed in neuronal ceroid lipofuscinosis (NCL) or Batten disease, LASS5 can increase ceramide levels and partially correct growth and apoptosis. |