Assembly of the Alu domain of the signal recognition particle (SRP): dimerization of the two protein components is required for efficient binding to SRP RNA.
AUTOR(ES)
Strub, K
RESUMO
The signal recognition particle (SRP), a cytoplasmic ribonucleoprotein, plays an essential role in targeting secretory proteins to the rough endoplasmic reticulum membrane. In addition to the targeting function, SRP contains an elongation arrest or pausing function. This function is carried out by the Alu domain, which consists of two proteins, SRP9 and SRP14, and the portion of SRP (7SL) RNA which is homologous to the Alu family of repetitive sequences. To study the assembly pathway of the components in the Alu domain, we have isolated a cDNA clone of SRP9, in addition to a previously obtained cDNA clone of SRP14. We show that neither SRP9 nor SRP14 alone interacts specifically with SRP RNA. Rather, the presence of both proteins is required for the formation of a stable RNA-protein complex. Furthermore, heterodimerization of SRP9 and SRP14 occurs in the absence of SRP RNA. Since a partially reconstituted SRP lacking SRP9 and SRP14 [SRP(-9/14)] is deficient in the elongation arrest function, it follows from our results that both proteins are required to assemble a functional domain. In addition, SRP9 and SRP14 synthesized in vitro from synthetic mRNAs derived from their cDNA clones restore elongation arrest activity to SRP(-9/14).
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=360878Documentos Relacionados
- Identification of RNA sequences and structural elements required for assembly of fission yeast SRP54 protein with signal recognition particle RNA.
- Isolation and characterization of a cDNA clone encoding the 19 kDa protein of signal recognition particle (SRP): expression and binding to 7SL RNA.
- Conserved tertiary base pairing ensures proper RNA folding and efficient assembly of the signal recognition particle Alu domain
- Binding site of the M-domain of human protein SRP54 determined by systematic site-directed mutagenesis of signal recognition particle RNA.
- Binding sites of the 9- and 14-kilodalton heterodimeric protein subunit of the signal recognition particle (SRP) are contained exclusively in the Alu domain of SRP RNA and contain a sequence motif that is conserved in evolution.