C-C chemokine receptor type 9 is a protein that in humans is encoded by the CCR9 gene.

The protein encoded by this gene is a member of the beta chemokine receptor family. It is predicted to be a seven transmembrane protein similar to G protein-coupled receptors. Chemokines and their receptors are key regulators of the thymocytes migration and maturation in normal and inflammation conditions. The specific ligand of this receptor is CCL25. It has been found that this gene is differentially expressed by T lymphocytes of small intestine and colon, suggested a role in the thymocytes recruitment and development that may permit functional specialization of immune responses in different segment of the gastrointestinal tract. This gene is mapped to the chemokine receptor gene cluster region. Two alternatively spliced transcript variants have been described. [provided by RefSeq, Jul 2008].
Function: Receptor for chemokine SCYA25/TECK. Subsequently transduces a signal by increasing the intracellular calcium ions level. Alternative coreceptor with CD4 for HIV-1 infection.