Functions as a calcium- and diacylglycerol (DAG)-regulated nucleotide exchange factor specifically activating Ras through the exchange of bound GDP for GTP (PubMed:15899849, PubMed:23908768, PubMed:27776107, PubMed:29155103). Activates the Erk/MAP kinase cascade (PubMed:15899849). Regulates T-cell/B-cell development, homeostasis and differentiation by coupling T-lymphocyte/B-lymphocyte antigen receptors to Ras (PubMed:10807788, PubMed:12839994, PubMed:27776107, PubMed:29155103). Regulates NK cell cytotoxicity and ITAM-dependent cytokine production by activation of Ras-mediated ERK and JNK pathways (PubMed:19933860). Functions in mast cell degranulation and cytokine secretion, regulating FcERI-evoked allergic responses. May also function in differentiation of other cell types (PubMed:12845332). Autoinhibited. Activated by diacylglycerol and calcium binding, which induces a conformational change releasing the autoinhibitory state (PubMed:23908768). Regulated by DGKA (PubMed:11919165). Regulated by DGKZ (PubMed:11257115). Regulated by PLC gamma and F-actin polymerization (PubMed:12839994). Homodimer (PubMed:23908768). Forms a signaling complex with DGKZ and HRAS (PubMed:11257115). Interacts with F-actin (PubMed:12839994). Interacts with SKAP1 (PubMed:17658605). Found both in the cytosol and associated with membranes. Relocalization to the cell membrane upon activation is F-actin-dependent. Translocates to the Golgi in response to phorbol ester or nerve growth factor. Localizes to somata and dendrites but not to axons of hippocampal pyramidal cells (By similarity). Additional isoforms seem to exist. Several splicing events may be used independently in a modular way. Expressed in brain with higher expression in cerebellum, cerebral cortex and amygdala. Expressed in the hematopoietic system. Expressed in T-cells (at protein level). Expressed in NK cells (at protein level) (PubMed:19933860). Expressed in fetal brain and kidney. The phorbol-ester/DAG-type zinc finger is the principal mediator of the targeting to membranes and is required for functional activation through DAG-binding. Two EF-hand domains are present. However, only EF-hand 1 (and not EF-hand 2) binds calcium. Disease susceptibility is associated with variants affecting the gene represented in this entry. Aberrantly spliced isoforms and/or diminished levels of RASGRP1 are found in a cohort of SLE patients raising the possibility that dysregulation of this signaling protein contributes to the development of autoimmunity in a subset of SLE patients. The disease is caused by variants affecting the gene represented in this entry. Belongs to the RASGRP family. Contaminating sequence. Potential poly-A sequence.