Alternative titles; symbols
HGNC Approved Gene Symbol: ITSN2
Cytogenetic location: 2p23.3 Genomic coordinates (GRCh38) : 2:24,202,864-24,361,368 (from NCBI)
Intersection-2 is an Src homology-3 (SH3)-containing protein involved in clathrin-mediated endocytosis (Pucharcos et al., 2000).
By screening a human prostate cancer cell line cDNA expression library with an SH3 ligand peptide, Sparks et al. (1996) isolated several cDNAs encoding SH3 domain-containing proteins, including SH3D1B (ITSN2), which they called SH3P18. The partial SH3D1B cDNA encodes a predicted adaptor-like protein containing at least 3 SH3 domains. SH3 domains are 60-amino acid regions of limited sequence similarity among a number of signaling and cytoskeletal proteins. Despite their modest similarity, SH3 domains share a common function: they mediate protein-protein interactions by binding short proline-rich regions in target proteins. Each SH3 domain selects peptides sharing a different consensus motif, indicating that different SH3 domains prefer ligands with distinct sequence characteristics (summary by Sparks et al., 1996).
By EST database searching with ITSN1 (602442) as a template, followed by RT-PCR and RACE analysis of human brain and liver tissues, Pucharcos et al. (2000) isolated a full-length cDNA encoding ITSN2. Sequence analysis predicted that the 1,696-amino acid protein possesses 2 EH domains, a coiled-coil region, 5 consecutive central SH3 domains in the short isoform, and C-terminal DH, PH, and C2 domains in the long isoform. Northern blot analysis revealed ubiquitous expression of 10-, 8-, and 6.5-kb transcripts, with the longer transcript primarily expressed in adult heart and liver. Western blot analysis showed that expressed tagged long and short ITSN2 migrated in agreement with their predicted molecular weights of 193- and 142-kD, respectively. Immunofluorescence microscopy demonstrated sparse punctate expression throughout the cytoplasm for both ITSN1 and ITSN2, with ITSN1 having a more marked perinuclear pattern and a concentration in Golgi-like structures.
Pucharcos et al. (2000) found that overexpression of either of the ITSN2 isoforms or ITSN1 resulted in the inhibition of transferrin uptake and the blockage of clathrin-mediated endocytosis. Clathrin-mediated endocytosis occurs in coated vesicles at the plasma membrane and is critical in synaptic vesicle recycling in neurons and in the internalization of receptor-ligand complexes. The main component of clathrin-coated vesicles (CCVs) is the CLTC (118955), which associates with the smaller CLTA (118960) to form triskelions that organize themselves into a caged lattice forming the scaffold of nascent CCV. Pucharcos et al. (2000) concluded that ITSN1 and ITSN2 have a great variety of interacting domains and likely act as scaffolding proteins in clathrin-mediated endocytosis.
Scott (2001) mapped the ITSN2 gene to chromosome 2 based on sequence similarity between the ITSN2 sequence (GenBank AF182198) and chromosome 2 clones (GenBank AC008073 and AC009228).
Pucharcos, C., Estivill, X., de la Luna, S. Intersectin 2, a new multimodular protein involved in clathrin-mediated endocytosis. FEBS Lett. 478: 43-51, 2000. [PubMed: 10922467] [Full Text: https://doi.org/10.1016/s0014-5793(00)01793-2]
Scott, A. F. Personal Communication. Baltimore, Md. 2/20/2001.
Sparks, A. B., Hoffman, N. G., McConnell, S. J., Fowlkes, D. M., Kay, B. K. Cloning of ligand targets: systematic isolation of SH3 domain-containing proteins. Nature Biotech. 14: 741-744, 1996. [PubMed: 9630982] [Full Text: https://doi.org/10.1038/nbt0696-741]