TREML2 is a single-pass type I membrane protein, and it contains 1 Ig-like V-type (immunoglobulin-like) domain. It is a cell surface receptor that may play a role in the innate and adaptive immune response. TREML2 is located in a gene cluster on chromosome 6 with the single Ig variable (IgV) domain activating receptors TREM1 and TREM2, but it has distinct structural and functional properties. TREML2 is expressed throughout B cell development in addition to being expressed on macrophages and neutrophils and is the only TREM molecule to be found on lymphocytes. TREML2 is expressed on B lineage cells early in development, and the highest level of expression is detected on those mature peripheral B cell subpopulations that are involved in the initial humoral immune response against bacterial pathogens. TREML2 is unique in that it lacks either the conserved transmembrane lysine residue or ITAM/ITIMs within its own cytoplasmic domain. Thus, TREML2 does not exhibit any of the features associated with classical tyrosine-based signaling. Monocytes in the bone marrow or peripheral blood do not express detectable levels of TREML2, but its expression is up-regulated in conjunction with differentiation into macrophages. TREML2 is present on neutrophils in the bone marrow as well as the periphery, and inflammatory stimuli result in a dramatic increase in the expression of TREML2 on these cells in vivo.

Cell membrane; Single-pass type I membrane protein.