Empty site forms of the SRP54 and SRalpha GTPases mediate targeting of ribosome-nascent chain complexes to the endoplasmic reticulum

Article Abstract:

The interaction between the signal recognition particle (SRP) and the SRP receptor in the sarcoplasmic reticulum (SR) mediates the signal sequence-dependent attachement of ribosomes to the Sec61 complex. Nucleotide binding and hydrolysis during protein translocation was also dependent on SRalpha and SRP54 guanosine triphosphatases which mediated the guanosine triphosphate hydrolysis-dependent dissociation of SRP from the receptor and permitted the reutilization of SRP and SR for subsequent targeting cycles.

Carrier proteins, Transport proteins, Protein binding, Hydrolysis, Sarcoplasmic reticulum

A viral movement protein prevents spread of the gene silencing signal in Nicotiana benthamiana

Article Abstract:

A viral movement protein has been found to prevent spread of the Nicotiana benthamiana gene-silencing signal, as demonstrated with potato virus X. In plants viruses induce RNA-mediated defence much like posttranscriptional gene silencing (PTGS). A branch common to virus-and transgene-induced PTGS is blocked by the 25kDa viral movement protein (p25). Likely it generates the systemic silencing signal. No systemic silencing was detected unless p25 was inactivated.

Genetic aspects, Plant molecular genetics, Nicotiana, Plant viruses

Role of Sec61alpha in the regulated transfer of the ribosome-nascent chain complex from the signal recognition particle to the translocation channel

Article Abstract:

Results demonstrate that Sec61alpha is a structural core of the protein translocation channel of the mammalian endoplasm reticulum. Data point out that Sec61 complex has a role in regulating GTP hydrolysis of the signal recognition particle and the receptor complex.

Analysis, Proteins, Aminohydrolases, Signal peptides