Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.64 (MPP)
 1,876 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent progress is summarized on the mechanism of phototransduction by sensory rhodopsin I (SR-I), a phototaxis receptor in Halobacterium halobium. Two aspects are emphasized: (i) The coupling of retinal isomerization to protein conformational changes. Retinal analogs have been used to probe chromophore-apoprotein interactions during the receptor activation process. One of the most important results is the finding of a steric trigger deriving from the interaction of residues on the protein with a methyl group near the isomerizing bond of the retinal (at carbon 13). Recent work on molecular genetic methods to further probe structure/function includes the synthesis and expression of an SR-I apoprotein gene designed for residue replacements by cassette mutagenesis, and transformation of an H. halobium mutant lacking all retinylidene proteins known in this species to SR-I+ and bacteriorhodopsin (BR)+. (ii) The relay of the SR-I signal to a post-receptor component. A carboxylmethylated protein ("MPP-I") associated with SR-I and found in the H. halobium membrane exhibits homology with the signaling domain of eubacterial chemotaxis transducers (e.g., Escherichia coli Tar, Tsr, and Trg proteins), suggesting a model based on SR-I----MPP-I signal relay.
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PMID:Sensory rhodopsin I: receptor activation and signal relay. 152 61

To investigate the relationship between post-translational processing of the Rieske iron-sulfur protein of Saccharomyces cerevisiae and its assembly into the mitochondrial cytochrome bc1 complex we used iron-sulfur proteins in which the presequences had been changed by site-directed mutagenesis of the cloned iron-sulfur protein gene, so that the recognition sites for the matrix processing peptidase or the mitochondrial intermediate peptidase (MIP) had been destroyed. When yeast strain JPJ1, in which the gene for the iron-sulfur protein is deleted, was transformed with these constructs on a single copy expression vector, mitochondrial membranes and bc1 complexes isolated from these strains accumulated intermediate length iron-sulfur proteins in vivo. The cytochrome bc1 complex activities of these membranes and bc1 complexes indicate that intermediate iron-sulfur protein (i-ISP) has full activity when compared with that of mature sized iron-sulfur protein (m-ISP). Therefore the iron-sulfur cluster must have been inserted before processing of i-ISP to m-ISP by MIP. When iron-sulfur protein is imported into mitochondria in vitro, i-ISP interacts with components of the bc1 complex before it is processed to m-ISP. These results establish that the iron-sulfur cluster is inserted into the apoprotein before MIP cleaves off the second part of the presequence and that this second processing step takes place after i-ISP has been assembled into the bc1 complex.
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PMID:Intermediate length Rieske iron-sulfur protein is present and functionally active in the cytochrome bc1 complex of Saccharomyces cerevisiae. 1009 99