Crystal structure of the PB1 domain of NBR1

The scaffold protein NBR1 is involved in signal transmission downstream of the serine/protein kinase from the giant muscle protein titin. Its N-terminal Phox and Bem1p (PB1) domain plays a critical role in mediating protein-protein interactions with both titin kinase and with another scaffold protein, p62. We have determined the crystal structure of the PB1 domain of NBR1 at 1.55 angstrom resolution. It reveals a type-A PB1 domain with two negatively charged residue clusters. We provide a structural perspective on the involvement of NBR1 in the titin kinase signalling pathway. (c) 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.