Neurexins are a family of proteins that function in the
vertebrate nervous system as cell adhesion molecules and receptors.
They are encoded by several unlinked genes of which two, NRXN1 and
NRXN3, are among the largest known human genes. Three of the genes
(NRXN1-3) utilize two alternate promoters and include numerous
alternatively spliced exons to generate thousands of distinct mRNA
transcripts and protein isoforms. The majority of transcripts are
produced from the upstream promoter and encode alpha-neurexin
isoforms; a much smaller number of transcripts are produced from
the downstream promoter and encode beta-neurexin isoforms. The
alpha-neurexins contain epidermal growth factor-like (EGF-like)
sequences and laminin G domains, and have been shown to interact
with neurexophilins. The beta-neurexins lack EGF-like sequences and
contain fewer laminin G domains than alpha-neurexins. [provided by
RefSeq].
