Retinoid protein

It triggers conformational changes In retinoid proteins, such as rhodop-sin, relevant to vision, and bacterlorhodopsin, relevant to ATP synthesis. (Adapted from Saito and Kobayashi, 2002)... 

It triggers conformational changes in retinoid proteins, such as rhodopsin and bacteriorhodopsin, relevant to vision and ATP synthesis, respectively. 

The most widely used method to study retinoid-protein interactions is fluorescence titration. The strong absorbance of retinol and retinol analogs in the region of emission of protein tryptophans is associated with an efficient energy transfer from excited tryptophans to the bound retinoid, and leads to a substantial quenching of intrinsic protein fluorescence when retinoids interact with... 

The specific role of vitamin A in tissue differentiation has been an active area of research. The current thinking, developed in 1979, involves initial dehvery of retinol by holo-B >V (retinol-binding protein) to the cell cytosol (66). Retinol is then ultimately oxidized to retinoic acid and binds to a specific cellular retinoid-binding protein and is transported to the nucleus. Retinoic acid is then transferred to a nuclear retinoic acid receptor (RAR), which enhances the expression of a specific region of the genome. Transcription occurs and new proteins appear during the retinoic acid-induced differentiation of cells (56). 

The antagonist-induced conformation of nuclear hormone receptors attracts co-repressors like Nco/SMRT (nuclear hormone receptor co-repressor/silencing mediator of retinoid and thyroid receptors) which further recruit other nuclear proteins with histone deacetylase activity. Their action leads to chromatin condensation, thus preventing the general transcription apparatus from binding to promoter regions. 

Kang S, Duell EA, Fisher GJ, et al (1995) Application of retinol to human skin in vivo induces epidermal hyperplasia and cellular retinoid binding proteins characteristic of retinoic acid but without measurable retinoic acid levels or irritation. J Invest Dermatol 105 549-556... 

Horiguchi, T., Nishikawa, T., and Ohta, Y. et al. (2007). Retinoid X receptor gene expression and protein content in tissues of the rock sheU Thais clavigera. Aquatic Toxicology 84, 379-388. 

Types Steroids, iodothyro-nines, calcitriol, retinoids Polypeptides, proteins, glycoproteins, catecholamines... 

By selectively affecting gene transcription and the consequent production of appropriate target mRNAs, the amounts of specific proteins are changed and metabolic processes are influenced. The influence of each of these hormones is quite specific generally, the hormone affects less than 1% of the genes, mRNA, or proteins in a target cell sometimes only a few are affected. The nuclear actions of steroid, thyroid, and retinoid hormones are quite well defined. Most evidence sug-... 

Wang, X.D. et al., Retinoid signaling and activator protein-1 expression in ferrets given beta-carotene supplements and exposed to tobacco smoke, J. Natl. Cancer Inst., 91, 60, 1999. 

Rogers, M., J. M. Berestecky, M. Z. Hossain et al. 1990. Retinoid-enhanced gap junctional communication is achieved by increased levels of connexin 43mRNA and protein. Mol Carcinog 3(6) 335-343. 

Rhodopsin is a seven ot-helix trans-membrane protein and visual pigment of the vertebrate rod photoreceptor cells that mediate dim light vision. In this photoreceptor, retinal is the chromophore bound by opsin protein, covalently linked to Lys296 by a Schiff base linkage. Kpega et al.64 have studied NMR spectra of Schiff bases being derivatives of all-frans retinal and amino-p-cyclodextrins as a model of rhodopsin, where p-cyclodextrin plays a role of a binding pocket. On the basis of analysis of the chemical shift differences for the model compound in the presence and in the absence of adamantane carboxylate, it has been shown that the derivative of 3-amino-p-cyclodextrin forms dimer in water and retinoid is inserted into p-cyclodextrin cavity [31]. 

Two important cis-acting elements in the ALDH2 promoter have been studied. A site located from 79 to 116 bp upstream of the ATG initiating translation is bound by nuclear factor(s) present in all cells tested the CCAAT box in this region is important for transcriptional activity, and appears to be bound primarily by the transcription factor NF-Y/CP1 [46]. There is a site, approximately 300 bp upstream of the ATG, at which HNF-4 and retinoid X receptors can bind, as can the apolipoproteins regulatory protein (ARP-1) [47, 48]. Transcription from this promoter can be activated by HNF-4 and RXRs [47, 48]. 

Fig. 4-11). Interestingly, the larger amounts of P2 protein that are in myelin of some species correlate with increased widths of the major dense lines as determined by X-ray diffraction, and there appears to be substantially more P2 in large sheaths than small ones [4]. The large variation in the amount and distribution of the protein from species to species and sheath to sheath raises so far unanswered questions about its function. Its similarities to cytoplasmic proteins in other cells, whose functions appear to involve solubilization and transport of fatty acids and retinoids, suggest that it might function similarly in myelin assembly or turnover, but there is currently no direct experimental evidence to support this hypothesis. 

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