Cell Molec! 2 Ste5 binds to the beta and gamma subunits of the active G-protein.
ID: 38257 • Letter: C
Question
Cell Molec! 2
Ste5 binds to the beta and gamma subunits of the active G-protein.
If you cross (delta)Ste5 and Ste11, generating an (delta)Ste5/Ste11 double mutant, the mutant shows the same phenotype as the (delta)Ste5 single subunit.
Cell Molec! 2 Ste5 binds to the beta and gamma subunits of the active G-protein. If you cross (delta)Ste5 and Ste11, generating an (delta)Ste5/Ste11 double mutant, the mutant shows the same phenotype as the (delta)Ste5 single subunit. What does this indicated about the signaling sequence?Explanation / Answer
Answer:
Abstract
A vector based upon the calmodulin-ubiquitin 2.65 locus of Trypanosoma cruzi has enabled the expression and secretion of the murine cytokines interleukin-2 (IL-2) and gamma-interferon (gamma-IFN) by transfected T. cruzi. The T. cruzi-derived cytokines were bioactive and produced by both epimastigotes and mammalian forms. The native coding sequence of IL-2 was sufficient to cause secretion of the protein, but the gamma-IFN signal sequence had to be replaced by the IL-2 signal sequence (IL-2/gamma-IFN) to allow efficient secretion of gamma-IFN. The amino acid sequences at the N-termini of the secreted T. cruzi-derived cytokines were different from the expected murine secreted protein. The secreted IL-2 was cleaved six amino acids downstream from the murine signal sequence cleavage site, and the hybrid IL-2/gamma-IFN molecule was cleaved three amino acids downstream from the predicted signal cleavage site in the IL-2/gamma-IFN molecule. These apparent differences in signal peptide sequence requirements and cleavage sites most likely indicate that the signal sequence processing in trypanosomes is distinct from that of higher eukaryotes.