ABSTRACT
Signaling proteins comprised of modular domains have evolved along with multicellularity as a method to facilitate increasing intracellular bandwidth. The effects of intramolecular interactions between modular domains within the context of native proteins have been largely unexplored. Here we examine intra- and intermolecular interactions in the multidomain signaling protein, protein kinase Cα (PKCα). We identify three interactions between two activated PKC molecules that synergistically stabilize a nanomolar affinity homodimer. Disruption of the homodimer results in a loss of PKC-mediated ERK1/2 phosphorylation, whereas disruption of the auto-inhibited state promotes the homodimer and prolongs PKC membrane localization. These observations support a novel regulatory mechanism wherein homodimerization dictates the equilibrium between the auto-inhibited and active states of PKC by sequestering auto-inhibitory interactions. Our findings underscore the physiological importance of context-dependent modular domain interactions in cell signaling.
Subject(s)
Cell Membrane/enzymology , Protein Kinase C-alpha/metabolism , Protein Multimerization/physiology , Signal Transduction/physiology , Animals , CHO Cells , Cell Membrane/chemistry , Cell Membrane/genetics , Cricetinae , Cricetulus , Humans , Mitogen-Activated Protein Kinase 1/chemistry , Mitogen-Activated Protein Kinase 1/genetics , Mitogen-Activated Protein Kinase 1/metabolism , Mitogen-Activated Protein Kinase 3/chemistry , Mitogen-Activated Protein Kinase 3/genetics , Mitogen-Activated Protein Kinase 3/metabolism , Protein Kinase C-alpha/chemistry , Protein Kinase C-alpha/genetics , Protein Structure, TertiaryABSTRACT
Coordinating behavior of novel N2O type mixed ligand complexes (1-6) have been synthesized from substituted fluoropyrimidine [5-Fluorouracil (5-FU; A)] with biopotent imidazole enzyme constituents (B) viz., imidazole(him) and benzimidazole(bim) in the presence of Ni(II), Cu(II) and Zn(II) ions. Synthesized complexes were characterized by chemical analysis, spectral studies, magnetic moment and conductivity measurements. The results of chemical analysis and the observed low molar conductance values propose their stoichiometry to be 1:1:1 (M:A:B) with non-electrolytic nature. From the spectral data, it is inferred that the ligands A & B coordinate with M(II) ions in bi and monodentate approach through C(4)=O, N(3) and imidazole ring N(3) atoms respectively. The thermogravimetric analysis shows the dehydration, decomposition and thermal stability of mixed ligand complexes. XRD and SEM patterns show sharp crystalline peaks with homogeneous morphology. In vitro antimicrobial activities of free ligands (A & B) and their metal complexes were screened against some pathogenic strains by well diffusion technique. Absorption and gel electrophoresis experiments on the interaction of mixed ligand complexes with DNA suggest that all the complexes can bind as well as cleave the DNA by intercalation between chromophores and DNA base pairs. In addition, in vitro antioxidant activities were tested by DPPH free radical scavenging model.
Subject(s)
Antimetabolites/chemistry , Antioxidants/chemistry , Coordination Complexes/chemistry , Fluorouracil/analogs & derivatives , Imidazoles/chemistry , Pyrimidines/chemistry , Animals , Antimetabolites/pharmacology , Antioxidants/pharmacology , Bacteria/drug effects , Bacterial Infections/drug therapy , Cattle , Coordination Complexes/pharmacology , Copper/chemistry , Copper/pharmacology , DNA/chemistry , DNA Cleavage/drug effects , Fluorouracil/pharmacology , Fungi/drug effects , Humans , Imidazoles/pharmacology , Ligands , Microbial Sensitivity Tests , Mycoses/drug therapy , Nickel/chemistry , Nickel/pharmacology , Pyrimidines/pharmacology , Zinc/chemistry , Zinc/pharmacologyABSTRACT
PURPOSE: The aim of this study was to assess the effect of a palatal lift prosthesis (PLP) on the speech intelligibility of cleft palate patients treated with pharyngeal flap surgery, the minimum duration required for improvement in nasality, and the sustenance of speech improvement after removing the appliance. MATERIALS AND METHODS: Seven patients ranging between 16 and 26 years of age were recruited for this study. These subjects had velopharyngeal dysfunction secondary to a surgically corrected cleft palate, which failed to improve following pharyngeal flap surgery. A PLP was given to these patients and improvements in speech intelligibility were assessed using two speech examinations: perceptual analysis and nasometry. The nasal resonance, nasal air emission, and articulation were measured prior to the insertion of the prosthesis and at the end of every month for the next 3 months, following which the prosthesis was removed and the tests were repeated. RESULTS: There was a statistically significant decrease in nasalance percentage at the end of the 3 months, and it was found that this improvement in speech persisted even after the removal of the prosthesis. CONCLUSIONS: A PLP, when used for a minimum duration of 3 months, causes a significant decrease in nasal resonance, thereby improving speech intelligibility in patients who failed to see improvement following pharyngeal flap surgery for velopharyngeal incompetence.
