Guanine nucleotide-binding protein G(k) subunit alpha - P08754 (GNAI3_HUMAN)


Protein Feature View of PDB entries mapped to a UniProtKB sequence  

Heterotrimeric guanine nucleotide-binding proteins (G proteins) function as transducers downstream of G protein-coupled receptors (GPCRs) in numerous signaling cascades. The alpha chain contains the guanine nucleotide binding site and alternates between an active, GTP-bound state and an inactive, GDP-bound state. Signaling by an activated GPCR promotes GDP release and GTP binding. The alpha subunit has a low GTPase activity that converts bound GTP to GDP, thereby terminating the signal. Both GDP release and GTP hydrolysis are modulated by numerous regulatory proteins (PubMed:8774883, PubMed:18434541, PubMed:19478087). Signaling is mediated via effector proteins, such as adenylate cyclase. Inhibits adenylate cyclase activity, leading to decreased intracellular cAMP levels (PubMed:19478087). Stimulates the activity of receptor-regulated K(+) channels (PubMed:2535845). The active GTP-bound form prevents the association of RGS14 with centrosomes and is required for the translocation of RGS14 from the cytoplasm to the plasma membrane. May play a role in cell division (PubMed:17635935). UniProt
Pathway Maps
      ESCHER  BiGG
Subunit Structure
Heterotrimeric G proteins are composed of 3 units; alpha, beta and gamma. The alpha subunit contains the guanine nucleotide binding site. GTP binding causes dissociation of the heterotrimer, liberating the individual subunits so that they can interact with downstream effector proteins. Forms a complex with CCDC88A/GIV and EGFR which leads to enhanced EGFR signaling and triggering of cell migration; ligand stimulation is required for recruitment of GNAI3 to the complex (PubMed:20462955). Interacts (inactive GDP-bound form) with CCDC88A/GIV (via GBA motif); the interaction leads to activation of GNAI3 (PubMed:19211784, PubMed:20462955). Interacts (inactive GDP-bound form) with CCDC88C/DAPLE (via GBA motif); the interaction leads to activation of GNAI3 (PubMed:26126266). Interacts (inactive GDP-bound form) with NUCB1 (via GBA motif) and NUCB2 (via GBA motif); the interaction leads to activation of GNAI3 (By similarity). Interacts (inactive GDP-bound form) with PLCD4 (via GBA motif); the interaction leads to activation of GNAI3 (PubMed:30194280). Interacts with INSR; the interaction is probably mediated by CCDC88A/GIV (PubMed:25187647). Interacts with GPSM1 (By similarity). Interacts (GDP-bound form) with GPSM2 (via GoLoco domains) (PubMed:22952234). Does not interact with RGS2 (PubMed:19478087). Interacts with RGS8 and RGS10; this strongly enhances the intrinsic GTPase activity (PubMed:8774883, PubMed:18434541). Interacts with RGS16; this strongly enhances the intrinsic GTPase activity (PubMed:19478087). Interacts with RGS12 (By similarity). Interacts (via active GTP- or inactive GDP-bound form) with RGS14 (By similarity). UniProt
The Protein Feature View requires a browser that supports SVG (Scalable Vector Graphics). Mouse over tracks and labels for more information.
Data origin/color codes
The vertical color bar on the left side indicates data provenance.
Data in green originates from UniProtKB  
Variation data (sourced from UniProt) shows non-genetic variation from the ExPASy   and dbSNP   websites.
Data in yellow originates from Pfam  , by interacting with the HMMER3 web site  
Data in purple originates from Phosphosite  .
Data in orange originates from the SCOP   (version 1.75) and SCOPe   (version 2.04) classifications.
Data in grey has been calculated using BioJava  . Protein disorder predictions are based on JRONN (Troshin, P. and Barton, G. J. unpublished), a Java implementation of RONN  
  • Red: potentially disorderd region
  • Blue: probably ordered region.
Hydropathy has been calculated using a sliding window of 15 residues and summing up scores from standard hydrophobicity tables.
  • Red: hydrophobic
  • Blue: hydrophilic.
Data in lilac represent the genomic exon structure projected onto the UniProt sequence.
Data in blue originates from PDB
  • Secstruc: Secondary structure projected from representative PDB entries onto the UniProt sequence.
Sequence Mismatches It is now possible to see information about expression tags, cloning artifacts, and many other details related to sequence mismatches.
Icons represent a number of different sequence modifications that can be observed in PDB files. For example the 'T' icon T represents expression tags that have been added to the sequence. The 'E' icon E represents an engineered mutation. However, besides these two, there are many other icons. For more information about the meaning and exact position of a sequence modification, move the cursor over the icon.
Validation Track

For more details on the Validation Track (Structure Summary Page only) see the dedicated help page.

Data in red indicates combined ranges of Homology Models from the SWISS-MODEL Repository  
The PDB to UniProt mapping is based on the data provided by the EBI SIFTS project. See also Velankar et al., Nucleic Acids Research 33, D262-265 (2005).
Organism icons generated by under CC BY. The authors are: Freepik, Icons8, OCHA, Scott de Jonge.

For more details on the Protein Feature view see the dedicated help page.