ABSTRACT
OBJECTIVE@#To investigate the effect of calmodulin (CaM) and its mutants on binding to voltage-gated Na channel isoleucine-glutamine domain (Na1.2 IQ).@*METHODS@#The cDNA of Na1.2 IQ was constructed by PCR technique, CaM mutants CaM, CaM and CaM were constructed with Quickchange site-directed mutagenesis kit (QIAGEN). The binding of Na1.2 IQ to CaM and CaM mutants under calcium and calcium free conditions were detected by pull-down assay.@*RESULTS@#Na1.2 IQ and CaM were bound to each other at different calcium concentrations, while GST alone did not bind to CaM. The binding affinity of CaM and Na1.2 IQ at [Ca]-free was greater than that at 100 nmol/L [Ca] ( < 0.05). In the absence of calcium, the binding amount of CaM wild-type to Na1.2 IQ was greater than that of its mutant, and the binding affinity of CaM to Na1.2 IQ was the weakest among the three mutants ( < 0.05).@*CONCLUSIONS@#The binding ability of CaM and CaM mutants to Na1.2 IQ is Ca-dependent. This study has revealed a new mechanism of Na1.2 regulated by CaM, which would be useful for the study of ion channel related diseases.
Subject(s)
Calcium , Metabolism , Calmodulin , Genetics , Metabolism , Mutation , Metabolism , Protein Binding , GeneticsABSTRACT
Objective To study the value and limitation of CT in the damage to multiple organs in children with Langerhans cell histiocytosis (LCH). Methods Analysis of CT manifestations was performed in 13 cases of LCH proved by clinical features, laboratory data, and pathologic changes. Localized LCH was found in 4 cases, and disseminated LCH in 9 cases. All cases were examined by plain scan in craniocerebral, chest, liver, and spleen, and four cases by contrast-enhanced CT scan. Results The male outnumbered female in this group. Cranial bones were involved in the sequence of temporal bone(8 cases), parietal bone (3 cases), occipital bone (2 cases), and frontal bone (1 case). CT findings were very sensitive in showing the early destructions of the bones. The characteristic manifestation on CT was multiple lytic lesions of the flat bones at any sites, without reactive sclerosis and soft tissue mass accompanied with the bony lesion. Imaging findings presented later than the clinical manifestations for LCH involving the hypothalamus/pituitary axis. Involvement of the lung at various stages by LCH could be demonstrated by CT scan. Conclusion Imaging manifestations had no characteristics in LCH involvement. The sites of predilection and related CT manifestations could be suggestive of the diagnosis. In addition, CT findings can be helpful in the classification and evaluation of the therapy and prognosis in LCH.