Pseudokinase domain of Nuclear Receptor Binding Protein 1 and similar proteins
The pseudokinase domain shows similarity to protein kinases but lacks crucial residues for catalytic activity and/or ATP binding. This subfamily is composed of NRBP1, also called MLF1-adaptor molecule (MADM), and MADML. NRBP1 was originally named based on the presence of nuclear binding and localization motifs prior to functional analyses. It is expressed ubiquitously and is found to localize in the cytoplasm, not the nucleus. NRBP1 is an adaptor protein that interacts with myeloid leukemia factor 1 (MLF1), an oncogene that enhances myeloid development of hematopoietic cells. It also interacts with the small GTPase Rac3. NRBP1 may also be involved in Golgi to ER trafficking. MADML (for MADM-Like) has been shown to be expressed throughout development in Xenopus laevis with highest expression found in the developing lens and retina. The NRBP1-like subfamily is part of a larger superfamily that includes the catalytic domains of serine/threonine kinases, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.