The Subunit Gene

The a2/8 subunit is a glycosylated membrane protein of 125,018 Da, which is processed post-translationally by proteolysis, resulting in an U2 pro- 

Four p subunit genes (Pi-P4) have been identified (Ruth et al., 1989 Hullin et al., 1992 Castellano et al., 

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Several groups have reported recessive, heteroaUelic mutations in the subunit gene in patients with nAChR deficiency or the low-affinity fast channel syndrome. 

Genes lux) encoding luciferase and the other proteias iavolved ia the bioluminescent reaction have been cloned. PuxA. and luxP genes code for the luciferase subunits, and the fatty acid reductase complex is coded by the luxCDE genes. 

Cohn, D. H., et al. (1985). Nucleotide sequence of the luxA gene of Vibrio harveyi and the complete amino acid sequence of the a subunit of bacterial luciferase. J. Biol. Chem. 260 6139-6146. 

Other examples include rifampin resistance due to mutations in the ipoB gene encoding the (3-subunit of RNA polymerase, or oxazolidinone resistance due to a G2576T mutation in the gene for the 23 S rRNA as central part of the 50S large ribosomal subunit. Macrolide resistance is based upon the alteration of nucleotide A2058 by a point mutation. 

These findings were unexpected because previous studies had demonstrated that the y2 subunit is required for potentiation of GABAa receptor function by low concentrations of ethanol [2]. The y2 subunit gene is located within a definitely mapped quantitative trait locus (QTL) for acute alcohol withdrawal on mouse chromosome 11 [1]. Allelic variation was genetically... 

Several diseases involving dysregulation of MR function have been described although most of them are not causatively linked to the receptor itself. Pseudohypoaldosteronism for example is a syndrome of mineralocorticoid resistance characterized by urinary salt loss and dehydration. However, only very rarely mutations in the MR gene have been found in these patients so far. In most cases, this syndrome appears to be linked to defects in the subunits of the amiloride-sensitive sodium channel ENaC, a major target of mineralocorticoid action in the kidney. 

The nifU gene product (NifU) from A. vinelandii has been overexpressed in E. coli and the recombinant protein purified and characterized (60). NifU is a homodimer of 33-kDa subunits with 2 Fe atoms per subunit. Spectroscopic studies showed the presence of [Fe2S2l clusters with = 254 mV and only cysteinyl coordination, but with... 

A preparation of the third nitrogenase from A. vinelandii, isolated from a molybdenum-tolerant strain but lacking the structural genes for the molybdenum and vanadium nitrogenases, was discovered to contain FeMoco 194). The 8 subunit encoded by anfG was identified in this preparation, which contained 24 Fe atoms and 1 Mo atom per mol. EPR spectroscopy and extraction of the cofactor identified it as FeMoco. The hybrid enzyme could reduce N2 to ammonia and reduced acetylene to ethylene and ethane. The rate of formation of ethane was nonlinear and the ethane ethylene ratio was strongly dependent on the ratio of nitrogenase components. 

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