HAMAP rule MF_00023

General rule information [?]

Accession	MF_00023
Dates	1-JUN-2001 (Created) 1-JUN-2023 (Last updated, Version 26)

Name

SmpB

Scope

Bacteria

Templates

P0A832 (SSRP_ECOLI); Q8RR57 (SSRP_THET8); O66640 (SSRP_AQUAE); O32230 (SSRP_BACSU): [Recover all]

Triggered by

Propagated annotation [?]

Identifier, protein and gene names [?]

Identifier

SSRP

Protein name

RecName:		Full=SsrA-binding protein;
AltName:		Full=Small protein B;

Gene name

smpB

Comments [?]

Function	Required for rescue of stalled ribosomes mediated by trans-translation. Binds to transfer-messenger RNA (tmRNA), required for stable association of tmRNA with ribosomes. tmRNA and SmpB together mimic tRNA shape, replacing the anticodon stem-loop with SmpB. tmRNA is encoded by the ssrA gene; the 2 termini fold to resemble tRNA(Ala) and it encodes a 'tag peptide', a short internal open reading frame. During trans-translation Ala-aminoacylated tmRNA acts like a tRNA, entering the A-site of stalled ribosomes, displacing the stalled mRNA. The ribosome then switches to translate the ORF on the tmRNA; the nascent peptide is terminated with the 'tag peptide' encoded by the tmRNA and targeted for degradation. The ribosome is freed to recommence translation, which seems to be the essential function of trans-translation.
Subcellular location	Cytoplasm. Note=The tmRNA-SmpB complex associates with stalled 70S ribosomes.
Similarity	Belongs to the SmpB family.

Keywords [?]

Gene Ontology [?]

GO:0003723; Molecular function: RNA binding.
GO:0005737; Cellular component: cytoplasm.
GO:0070929; Biological process: trans-translation.

Cross-references [?]

Additional information [?]