Contactin-associated protein-like 2 is a protein that in humans is encoded by the CNTNAP2gene. Since the most recent reference human genome GRCh38, CNTNAP2 is the longest gene in the human genome 
This gene encodes a member of the neurexin family which functions in the vertebrate nervous system as cell adhesion molecules and receptors. This protein, like other neurexin proteins, contains epidermal growth factor repeats and laminin G domains. In addition, it includes an F5/8 type C domain, discoidin/neuropilin- and fibrinogen-like domains, thrombospondin N-terminal-like domains and a putative PDZ binding site. This protein is localized at the juxtaparanodes of myelinated axons and associated with potassium channels. It may play a role in the local differentiation of the axon into distinct functional subdomains. This gene encompasses almost 1.6% of chromosome 7 and is one of the largest genes in the human genome. It may represent a positional candidate gene for the DFNB13 form of nonsyndromic deafness.
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