Alternative titles; symbols
HGNC Approved Gene Symbol: GIT2
Cytogenetic location: 12q24.11 Genomic coordinates (GRCh38) : 12:109,929,804-110,000,164 (from NCBI)
By affinity purification, screening a mouse fibroblast cDNA library, and 5-prime RACE, Bagrodia et al. (1999) cloned a full-length cDNA encoding mouse Git2, which they called Cat2, a 95-kD tyrosine-phosphorylated protein that bound a complex of Cool (see COOL1, or PIXB; 605477) and Pak3 (300142). The deduced 708-amino acid Git2 protein contains a Gcs (see ARFGAP1; 608377)-type C2C2H2 zinc finger motif, a triple ankyrin repeat region, and potential SH3-binding motifs. Mouse Git2 shares significant homology with GIT1 (608434) and 86% amino acid identity with the 50-kD human KIAA0148 protein (Nagase et al., 1995).
Premont et al. (2000) identified ESTs of human GIT2 based on their homology to GIT1. Using PCR, they determined that there are at least 10 alternatively spliced variants of GIT2, including KIAA0148. The longest GIT2 variant, GIT2-long, encodes a deduced 759-amino acid protein with a calculated molecular mass of 84.5 kD. It contains an N-terminal ADP-ribosylation factor-GTPase-activating protein (ARFGAP) domain, ankyrin repeats, and a C-terminal putative G protein-coupled receptor kinase (GRK) interaction domain. GIT2-long shares 64% amino acid identity with GIT1 and 89% identity with the chicken paxillin (PXN; 602505) kinase linker (Pkl) protein. The shortest variant, GIT2-short, corresponds to KIAA0148 and contains a truncated C terminus with 7 unique amino acids. RT-PCR and Northern blot analysis showed ubiquitous expression of GIT2 with tissue-specific alternative splicing. A GIT2-long C-terminal probe detected a widely expressed 6.5-kb transcript, a 2.8-kb transcript in testis, and several minor transcripts. A GIT2-short C-terminal probe detected a 4.4-kb transcript in brain and a 2.3-kb transcript in spleen, leukocytes, and, to a lesser extent, thymus.
Bagrodia et al. (1999) showed that mouse Git2 binds to the C-terminal regions of Cool2 (PIXA; 300267) and the 85-kD isoform of Cool1. Cell cycle and cell adhesion analyses indicated that tyrosine phosphorylation of Git2 increases with cell spreading on fibronectin, decreases during cell arrest in mitosis, and increases during the G1 phase of growth. Cotransfection of Git2 with Fak (600758) and Src (190090) revealed that these kinases can phosphorylate Git2.
Vitale et al. (2000) showed that human GIT2 could act as a GAP for GTP bound to ARFs. Plasma emission spectroscopy showed association of 1 zinc molecule per molecule of GIT2. Phosphatidylinositol 3,4,5-trisphosphate stimulated GIT2 hydrolysis of GTP bound to ARF proteins.
Premont et al. (2000) found that GIT2-long and GIT2-short have GAP activity with ARF1 (103180). Coimmunoprecipitation experiments indicated that GIT2 interacts with GRK2 (109635) and with PIX-PAK complexes. Overexpression of GIT2-long inhibited sequestration of beta-2-adrenergic receptor (109690) away from the cell surface.
Mazaki et al. (2001) coprecipitated GIT2 with the integrin signaling protein PXN. GIT2-long and GIT2-short bound to the N terminus of PXN-alpha, with GIT2-long showing a 10-fold higher affinity. Confocal immunofluorescence showed that GIT2-short colocalized with PXN at perinuclear areas and in actin-rich structures at the cell periphery. Using a variety of experiments, Mazaki et al. (2001) demonstrated GIT2-short had GAP activity on ARF1 in vitro and in vivo. Overexpression of GIT2-short antagonized several ARF1-mediated phenotypes: it caused redistribution of the Golgi protein BCOP (600959), a reduction in PXN-containing focal adhesions and actin stress fibers, and a reduction in the perinuclear localization of PXN.
By radiation hybrid analysis, Premont et al. (2000) mapped the GIT2 gene to chromosome 12q24.1.
Bagrodia, S., Bailey, D., Lenard, Z., Hart, M., Guan, J. L., Premont, R. T., Taylor, S. J., Cerione, R. A. A tyrosine-phosphorylated protein that binds to an important regulatory region on the Cool family of p21-activated kinase-binding proteins. J. Biol. Chem. 274: 22393-22400, 1999. [PubMed: 10428811] [Full Text: https://doi.org/10.1074/jbc.274.32.22393]
Mazaki, Y., Hashimoto, S., Okawa, K., Tsubouchi, A., Nakamura, K., Yagi, R., Yano, H., Kondo, A., Iwamatsu, A., Mizoguchi, A., Sabe, H. An ADP-ribosylation factor GTPase-activating protein Git2-short/KIAA0148 is involved in subcellular localization of paxillin and actin cytoskeletal organization. Molec. Biol. Cell 12: 645-662, 2001. [PubMed: 11251077] [Full Text: https://doi.org/10.1091/mbc.12.3.645]
Nagase, T., Seki, N., Tanaka, A., Ishikawa, K., Nomura, N. Prediction of the coding sequences of unidentified human genes. IV. The coding sequences of 40 new genes (KIAA0121-KIAA0160) deduced by analysis of cDNA clones from human cell line KG-1. DNA Res. 2: 167-174, 1995. [PubMed: 8590280] [Full Text: https://doi.org/10.1093/dnares/2.4.167]
Premont, R. T., Claing, A., Vitale, N., Perry, S. J., Lefkowitz, R. J. The GIT family of ADP-ribosylation factor GTPase-activating proteins: functional diversity of GIT2 through alternative splicing. J. Biol. Chem. 275: 22373-22380, 2000. [PubMed: 10896954] [Full Text: https://doi.org/10.1074/jbc.275.29.22373]
Vitale, N., Patton, W. A., Moss, J., Vaughan, M., Lefkowitz, R. J., Premont, R. T. GIT proteins, a novel family of phosphatidylinositol 3,4,5-trisphosphate-stimulated GTPase-activating proteins for ARF6. J. Biol. Chem. 275: 13901-13906, 2000. [PubMed: 10788515] [Full Text: https://doi.org/10.1074/jbc.275.18.13901]