1ffh
From Proteopedia
N AND GTPASE DOMAINS OF THE SIGNAL SEQUENCE RECOGNITION PROTEIN FFH FROM THERMUS AQUATICUS
Overview
The signal-recognition particle (SRP) and its receptor (SR) function in the co-translational targeting of nascent protein-ribosome complexes to the membrane translocation apparatus. The SRP protein subunit (termed Ffh in bacteria) that recognizes the signal sequence of nascent polypeptides is a GTPase, as is the SR-alpha subunit (termed FtsY). Ffh and FtsY interact directly, each stimulating the GTP hydrolysis activity of the other. The sequence of Ffh suggests three domains: an amino-terminal N domain of unknown function, a central GTPase G domain, and a methionine-rich M domain that binds both SRP RNA and signal peptides. Sequence conservation suggests that structurally similar N and G domains are present in FtsY. Here we report the structure of the nucleotide-free form of the NG fragment of Ffh. Consistent with a role for apo Ffh in protein targeting, the side chains of the empty active-site pocket form a tight network of interactions which may stabilize the nucleotide-free protein. The structural relationship between the two domains suggests that the N domain senses or controls the nucleotide occupancy of the GTPase domain. A structural subdomain unique to these evolutionarily conserved GTPases constitutes them as a distinct subfamily in the GTPase superfamily.
About this Structure
1FFH is a Single protein structure of sequence from Thermus aquaticus. Full crystallographic information is available from OCA.
Reference
Structure of the conserved GTPase domain of the signal recognition particle., Freymann DM, Keenan RJ, Stroud RM, Walter P, Nature. 1997 Jan 23;385(6614):361-4. PMID:9002524 Page seeded by OCA on Fri May 2 16:15:44 2008
