1/24/2024 0 Comments Otc rat 1 droppoint![]() (1985) gave the first reported example of an OTC gene deletion that could be identified cytogenetically in a patient with OTC deficiency ( 311250). Secondary structure predictions, distributions of hydrophilic and hydrophobic regions, and the pattern of conserved residues suggest that the 3-dimensional structures of the 2 proteins are likely to be similar. (1995) noted that the subunits of the human OTC homotrimer show 46% amino acid sequence homology to the catalytic subunit of E. ![]() In a review of the subject, Hurt and van Loon (1986) presented evidence that the amino-terminal presequences also contain information for 'intramitochondrial sorting.' The critical role of this arginine residue may be mediated by participation in a local secondary structure, very likely an alpha-helix. Further analysis of precursors with single substitutions revealed complete loss of function when arginine 23 was substituted with glycine. Analysis of deletions revealed that the mid-portion of the 32-residue leader peptide is an absolute requirement for both mitochondrial uptake and proteolytic processing. (1986) synthesized OTC precursors with alterations in the leader portion. To define the critical residues and/or regions in the OTC leader peptide, Horwich et al. The protein sequence resembles that of both OTC and aspartate transcarbamylase from E. ![]() The OTC enzyme is synthesized in the cytoplasm and is directed to mitochondria by a 32-residue amino-terminal leader peptide. This pre-OTC has an NH2-extension which is cleaved proteolytically concomitant with its posttranslational energy-dependent import into mitochondria. (1984) determined that the human OTC gene encodes a 354-amino acid protein which is synthesized on free cytoplasmic polyribosomes as a precursor of about 40 kD. The translated polypeptide has a molecular mass of 40 kD, but the authors noted that the mature, active enzyme is a trimer of identical 36-kD subunits, indicating posttranslational modification. (1983) isolated and characterized a cDNA corresponding to the OTC gene.
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