Presenilins

Presenilins are a family of related multi-pass transmembrane proteins that function as a part of the gamma-secretase protease complex. Presenilins undergo cleavage in an alpha helical region of one of the cytoplasmic loops to produce a larger N-terminal and a smaller C-terminal fragment which together form part of the functional protein. Cleavage of presenilin 1 can be prevented by a mutation which causes the loss of exon 9, and results in loss of function. Presenilins play a key role in the modulation of intracellular Ca²⁺ involved in presynaptic neurotransmitter release and long-term potentiation induction.

Dominant mutations in the genes that encode presenilin proteins are the most common cause of familial early-onset Alzheimer's disease.