LAX1 is a 398 amino acid single-pass type III membrane protein that negatively regulates lymphocyte signaling. LAX1 is expressed in lymphoid tissues including thymus, spleen and peripheral blood leukocytes, along with several B-cell, T-cell, natural killer and monocyte cell lines. When stimulated by B or T cells, LAX1 becomes dramatically upregulated and also interacts with GRB2, Gads and PI 3-kinase p85 upon phosphorylation. LAX1 exists as two alternatively spliced isoforms that are encoded by a gene located on human chromosome 1. Chromosome 1 houses a large number of disease-associated genes, including those that are involved in familial adenomatous polyposis, Stickler syndrome, Parkinson’s disease, Gaucher disease, schizophrenia and Usher syndrome.