Nuclear receptors (NRs) are a family of highly conserved transcription factors that regulate transcription in response to small lipophilic compounds. They play a role in every aspect of development, physiology and disease in humans. They are also ubiquitous in and unique to the animal kingdom suggesting that they may have played an important role in their evolution. In contrast to the classical endocrine receptors that originally defined the family, recent studies suggest that the first NRs might have been sensors of their environment, binding ligands that were external to the host organism. The purpose of this review is to provide a broad perspective on NR ligands and address the issue of exactly what constitutes a NR ligand from historical, biological and evolutionary perspectives.
Impact factor for the new journals will be considered after two years. Impact factor of a particular journal will give complete picture of the quality and standards of the journals. For example, if a journal has an impact factor of 5 in 2011, then its papers published in 2009 and 2010 received 5 citations each on average in 2011. The 2011 impact factor of a journal would be calculated as follows:
X = Number citation for the articles published during 2009 and 2010.
Y = the total number of articles published by that journal in 2009 and 2010
2011 impact factor = X/Y.
Last date updated on November, 2020