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RASGRP1
RAS guanyl releasing protein 1
RASGRP1 is located on the long (q) arm of chromosome 15, at band 15q14. Arm ratio per GRCh38 - banding schematic.
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Overview
RASGRP1 encodes a specialised signalling protein that functions as a molecular switch in immune cells, converting external signals from antigen receptors into intracellular responses through activation of RAS GTPases. The protein is particularly abundant in lymphocytes, where it translates calcium flux and lipid second messengers into sustained RAS pathway activation. Research suggests that variation in RASGRP1 contributes to polygenic risk for autoimmune conditions, likely through subtle alterations in immune cell activation thresholds. The gene is located on chromosome 15 and produces a 797-amino-acid protein with multiple functional domains that coordinate its response to immune receptor engagement.
What the gene does
The RASGRP1 protein acts as a guanine nucleotide exchange factor, catalysing the exchange of GDP for GTP on RAS family GTPases to promote their active state. This exchange activity is tightly regulated by calcium ions and diacylglycerol, two key second messengers generated when T-cell receptors or B-cell receptors encounter their cognate antigens. Upon receptor engagement, RASGRP1 translocates from the cytoplasm to cellular membranes, where it accesses RAS proteins embedded in the lipid bilayer. The protein's catalytic activity initiates downstream signalling cascades including the MAP kinase pathway, which controls immune cell proliferation, differentiation, and cytokine production. Evidence suggests that RASGRP1 establishes appropriate signalling thresholds during T-cell selection in the thymus, distinguishing cells that can recognise foreign antigens from those that inappropriately react to self-antigens. The protein also contributes to the development of natural killer T cells and regulatory T cells, specialised lymphocyte populations that modulate immune responses.
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Chromosome location
RASGRP1 is located on the long arm of chromosome 15 at position q14 (15q14). This chromosomal region contains multiple genes involved in immune regulation and cellular signalling. The gene spans a genomic region sufficient to encode the 797-amino-acid protein product through multiple exons, though the precise exon-intron architecture varies across published transcript assemblies.
Protein structure
The RASGRP1 protein comprises 797 amino acids organised into distinct functional modules. The N-terminal region includes an N-terminal Ras-GEF domain (amino acids 53-176) containing the Ras exchanger motif region (amino acids 57-110) required for transforming activity, followed by a larger Ras-GEF domain (amino acids 205-436) that executes the nucleotide exchange reaction. The central portion features two EF-hand domains (amino acids 470-505 and 506-532) that bind calcium ions, conferring calcium-dependent regulation of the protein's activity and localisation. A phorbol-ester/DAG-type zinc finger (amino acids 541-591) recognises diacylglycerol in cellular membranes, directing the protein to sites of active signalling. The C-terminal PT region (amino acids 718-797) mediates BCR-dependent translocation to the plasma membrane, whilst an upstream region (amino acids 686-694) suppresses this translocation in the absence of activation signals. A coiled-coil motif (amino acids 746-786) may facilitate protein-protein interactions. Disordered regions (amino acids 1-23 and 673-694) provide flexibility for conformational changes during activation.
Key variants
Genetic variation in RASGRP1 contributes to polygenic risk profiles for autoimmune conditions rather than following classical Mendelian inheritance patterns. Multiple common variants across the gene have been associated with subtle shifts in immune cell signalling thresholds. Unlike genes where single pathogenic variants cause disease directly, RASGRP1 variants typically exert small individual effects that combine with variation in other immune-related genes to influence overall disease susceptibility.
Sample of pathogenic variants
10 pathogenic / likely-pathogenic variants from ClinVar, ranked by review status (expert-panel-reviewed first). This is a sample; recurrent founder variants in a specific population may not appear here - see the full ClinVar listing via the link above.
| Variant (HGVS) | Protein change | Classification | Evidence | Associated condition |
|---|---|---|---|---|
c.2196_2199del | p.Ser732_Leu733insTer | Pathogenic/Likely pathogenic | ★★☆☆ | Immunodeficiency 64 |
c.241C>T | p.Arg81Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Immunodeficiency 64 |
c.327-1C>G | - | Pathogenic/Likely pathogenic | ★★☆☆ | Immunodeficiency 64 |
c.1024C>T | p.Arg342Ter | Pathogenic | ★☆☆☆ | not provided |
c.1232_1233del | p.His411fs | Pathogenic | ★☆☆☆ | Immunodeficiency 64 |
c.1720+1G>A | - | Pathogenic | ★☆☆☆ | Immunodeficiency 64 |
c.1720+2T>C | - | Pathogenic | ★☆☆☆ | Immunodeficiency 64 |
c.1910_1911dup | p.Ala638fs | Pathogenic | ★☆☆☆ | RASGRP1-related disorder |
c.353C>A | p.Ser118Ter | Pathogenic | ★☆☆☆ | not provided |
c.811C>T | p.Arg271Ter | Pathogenic | ★☆☆☆ | not provided |
Evidence stars indicate ClinVar review status. Individual variant interpretation should always be performed by a qualified clinical laboratory - many variants remain classified as Variants of Uncertain Significance (VUS) pending more research.
Associated conditions
RASGRP1 has been incorporated into polygenic risk scoring frameworks for autoimmune conditions, reflecting research that links variation in this gene to altered immune cell function. The protein's role in establishing appropriate activation thresholds during lymphocyte development means that variants affecting its expression or activity may contribute to the breakdown of self-tolerance observed in autoimmune disorders. Research continues to clarify how specific polymorphisms influence quantitative traits such as T-cell receptor signalling strength and regulatory T-cell frequency, which in turn affect population-level autoimmune disease risk.
No disease links recorded for this gene in our reference set.
UK clinical status
RASGRP1 appears on two NHS Genomic Medicine Service PanelApp panels with green classification status, indicating expert consensus that the gene has robust evidence for its role in specific clinical contexts. The gene is included in the COVID-19 research panel, reflecting investigation into genetic factors influencing immune responses to viral infection. It also features in the Primary immunodeficiency or monogenic inflammatory bowel disease panel (version R15), where it contributes to understanding immune dysregulation mechanisms. These panel memberships reflect evolving research into RASGRP1's role in immune system disorders rather than current routine clinical testing for single-gene conditions.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
What does the RASGRP1 protein do in immune cells?
RASGRP1 acts as a molecular switch that activates RAS proteins in response to antigen receptor signals, translating calcium flux and lipid messengers into sustained downstream signalling pathways that control lymphocyte development, activation, and tolerance. This function is essential for appropriate immune responses.
How does RASGRP1 variation influence autoimmune disease risk?
Variants in RASGRP1 contribute to polygenic risk profiles by subtly altering immune cell signalling thresholds. Unlike single-gene conditions, individual RASGRP1 polymorphisms have small effects that combine with variation in other immune genes to influence overall susceptibility to autoimmune disorders through mechanisms affecting self-tolerance.
Why is RASGRP1 included in NHS clinical panels?
RASGRP1 appears on NHS PanelApp panels for COVID-19 research and primary immunodeficiency or monogenic inflammatory bowel disease, reflecting its role in immune regulation. These inclusions support research into genetic factors affecting immune responses rather than indicating routine single-gene clinical testing for most patients.