Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
Nature. 1997 Jan 23;385(6614):361-4.

Structure of the conserved GTPase domain of the signal recognition particle.

Author information

  • 1Department of Biochemistry and Biophysics, School of Medicine, University of California, San Francisco 94143-0448, USA. freymann@msg.ucsf.edu

Abstract

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.

PMID:
9002524
[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Nature Publishing Group
    Loading ...
    Write to the Help Desk