Gene Summary: The protein encoded by IL-16 gene is a pleiotropic cytokine that functions as a chemoattractant, a modulator of T cell activation, and an inhibitor of HIV replication. The signaling process of this cytokine is mediated by CD4. The product of this gene undergoes proteolytic processing, which is found to yield two functional proteins. The cytokine function is exclusively attributed to the secreted C-terminal peptide, while the N-terminal product may play a role in cell cycle control. Caspase 3 is reported to be involved in the proteolytic processing of this protein. Alternate splicing results in multiple transcript variants. [provided by RefSeq, Feb 2010]General information above from NCBI
Subunit structure: Homotetramer (Probable). According to PubMed:9699630, the formation of a homotetrameric protein complex is not required for the chemo-attractant function. Isoform 3 interacts (via PDZ 3 domain) with PPP1R12A, PPP1R12B and PPP1R12C. Isoform 1 interacts with PPP1R12B. Isoform 3 interacts with GRIN2A. Isoform 3 interacts with GABPB1. Isoform 3 interacts (via PDZ 3 domain) with HDAC3. Isoform 1 interacts with GRIN2D, KCNJ10, KCNJ15 and CACNA1C (By similarity). Isoform 3 interacts with HTLV-1 tax.
Subcellular location: Interleukin-16: Secreted.
Isoform 1: Cytoplasm (By similarity).
Isoform 3: Cytoplasm. Nucleus.
Tissue specificity: Isoform 3 is expressed in hemopoietic tissues, such as resting T-cells, but is undetectable during active T-cell proliferation.
Induction: Isoform 3 is down-regulated in T-cells after TCR activation.
Post-translational: Isoform 3 is synthesized as a chemo-attractant inactive precursor in hemopoietic tissues and is proteolytically cleaved by caspase-3 to yield IL-16.
Sequence similarity: Contains 4 PDZ (DHR) domains.
General information above from UniProt