Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.16.2 (PCP)
 3,761 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The requirement of initiation factors F(1) (highly purified) and F(2) (electrophoretically homogeneous) for ribosomal binding of N-formylmethionyl transfer RNA (fMet approximately tRNA) at low Mg(2+) concentration (3.5 mM), with the trinucleoside diphosphate ApUpG as messenger, was studied under various experimental conditions with 30S + 50S ribosomes and with 30S subunits alone. The results were qualitatively the same in both cases but the amount of binding was two to three times higher when both 30S and 50S subunits were present. Although there was a virtually absolute requirement for F(2) in all cases, considerable binding occurred at 0 degrees in the absence of added F(1). F(1) addition stimulated binding up to twofold under these conditions. However, at 25 degrees , the temperature at which the reaction is usually carried out, there was very little binding with F(2) alone and addition of F(1) stimulated the reaction five- to sixfold. Contrary to current belief, the GTP analog 5'-guanylyldiphosphonate (GMP-PCP) cannot replace GTP in the binding reaction. In particular, there was but little stimulation of binding (about 1.5-fold) by addition of F(1) to F(2)-containing samples when GMP-PCP was used. In marked contrast, binding was stimulated up to sevenfold by addition of F(1) when GTP was substituted for the analog. Under these conditions, there was an ApUpG and F(1)-dependent hydrolysis of GTP. This is observable with 30S subunits alone and can hardly be related to the occurrence of translocation. The results may be interpreted to mean that a complex relatively stable at 0 degrees , but less stable at 25 degrees , is formed upon addition of F(2) alone. Conversion of the less stable to the more stable form of complex is made possible by addition of F(1). This is accompanied or mediated by cleavage of GTP.
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PMID:Polypeptide chain initiation in E. coli: studies on the function of initiation factor F1. 489 78

This article focuses on four human carboxypeptidases (CPs): two metallo-CPs and two serine CPs. The metallo-CPs are members of the so-called B-type regulatory CP family, as they cleave only the C-terminal basic amino acids Arg or Lys. The plasma membrane-bound CPM and the mainly, but not exclusively, intracellular CPD are surveyed from this group of enzymes. These enzymes can regulate peptide hormone activity at the cell surface and possibly intracellularly after receptor-mediated endocytosis and may also participate in peptide hormone processing. The serine CPs, as their name indicates, contain a serine residue in the active center essential for catalytic activity that reacts with organophosphorus inhibitors. Prolylcarboxypeptidase (PRCP) (angiotensinase C) and deamidase (cathepsin A, lysosomal protective protein) are discussed here. These two enzymes are highly concentrated in lysosomes; however, they may also be active extracellularly after their release from lysosomes in soluble form or in a plasma membrane-bound complex. Whereas deamidase cleaves a variety of peptides with C-terminal or penultimate hydrophobic residues (e.g. substance P, angiotensin I, bradykinin, endothelin, fMet-Leu-Phe). PRCP cleaves only peptides with a penultimate Pro residue (e.g. des-Arg9-bradykinin, angiotensin II). These enzymes may also be involved in terminating signal transduction by inactivating peptide ligands after receptor endocytosis.
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PMID:Cellular carboxypeptidases. 955 70