Protocadherin alpha 1 (PCDH alpha 1) is a group A member of the Protocadherin family of molecules. It is expressed in synaptic membranes of neurons, forms obligate Ca2+-independent complexes with various PCDH-gamma family members and demonstrates heterophilic binding activity towards beta1 integrins.
Human PCDH alpha 1 is 921 amino acids (aa) in length. It is a type I transmembrane glycoprotein that contains a 668 aa extracellular domain (ECD) plus a 232 aa cytoplasmic region. Both regions contribute to PCDH-gamma binding. There are six cadherin domains in the ECD. ADAM10 cleavage generates an 80 - 90 kDa soluble fragment and a soluble splice form exists that is missing aa 535 - 798. Over aa 30 - 689, human PCDH alpha 1 shares 83% aa identity with mouse PCDH alpha 1.