Midline-2 is a 715 amino acid protein encoded by the human gene MID2. Midline-2 belongs to the TRIM/RBCC family and contains two B box-type zinc fingers, one B30.2/SPRY domain, one COS domain, one fibronectin type-III domain and one RING-type zinc finger. Midline-2 is a cytoplasmic protein found as a homodimer or heterodimer with Midline-1. It also interacts with IGBP1 (Lymphocyte signaling protein A4). Dimerization is mediated by the tripartite motif (RBCC; RING- and B box-type zinc fingers and coiled coil domains) and microtubule association is dependent on the C-terminal B30.2 domain. Midline-2 is expressed at low levels in fetal kidney and lung, and in adult prostate, ovary and small intestine.