Actin cytoskeleton-organizing protein that plays a role in the formation of cell projections (By similarity). Required for actin polymerization at immunological synapses (IS) and for the recruitment of the chemokine receptor CXCR4 to IS (By similarity). Plays a role in dendritic spine morphogenesis and organization, including the localization of the dopamine receptor DRD1 to the dendritic spines (PubMed:25865831). Involved in memory-related synaptic plasticity in the hippocampus (PubMed:25865831). Interacts with RUFY3 (PubMed:24720729). Interacts with CXCR4; this interaction is enhanced by antigenic stimulation (By similarity). Interacts (via ADF-H domain) with ZMYND8 (via PHD-type Zinc finger, Bromo and PWWP domains); the interaction leads to sequestering of ZMYND8 in the cytoplasm (By similarity). In the absence of antigen, evenly distributed throughout subcortical regions of the T-cell membrane and cytoplasm. In the presence of antigen, distributes to the immunological synapse forming at the T-cell-APC contact area, where it localizes at the peripheral and distal supramolecular activation clusters (SMAC) (By similarity). Colocalized with RUFY3 and F-actin at the transitional domain of the axonal growth cone (PubMed:24720729). Additional isoforms seem to exist. Expressed in the hippocampus, with expression in the pyramidal cells of CA1, CA2 and CA3 and in the granule cells of the dentate gyrus (at protein level) (PubMed:25865831). Highly expressed in brain, also present in stomach and to a lesser degree in kidney, colon, and urinary bladder (PubMed:10633083). The E2 isoform is specifically expressed in adult stomach, kidney, and cultured cells (PubMed:10633083). Mice are born at the expected Mendelian frequency (PubMed:25865831). Mutant mice exhibit significant reduction of dendritic spine numbers, altered dendritic spine morphology with a reduction in the number of mushroom, thin and stubby types of dendritic spines, decreased protein levels of the neurotransmitter receptors DRD1, DRD2, HTR1A and 5HT7R and reduced numbers of DRD1 receptors on dendritic spines (PubMed:25865831). Inhibited memory-related high-frequency-induced synaptic strengthening (PubMed:25865831).