Receptor Classification by Mode of Action

Nuclear receptors can be grouped into four classes based on their DNA-binding and dimer-ization properties (Fig. 3.4).25 Generally speaking, class I receptors include GRs, mineralcorti-coid receptors (MRs), progesterone receptors (PRs), and androgen receptors (ARs), which function as homodimers and bind to IRs separated by 3 base pairs (i.e., IR-3). An exception to this rule is the estrogen receptors (ERs) which can form either heterodimers or homodimers on IR-3.30-32 Class II receptors require het-erodimerization with RXR family members and bind to DRs, varying from DR-1 to DR-5. The spacing, in general, specifies the identity of the dimerization partner. Class III receptors, including hepatocyte nuclear factor 4 (HNF-4), chicken ovalbumin upstream promoter-transcription factor (COUP-TF), and germ cell nu-

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Confident Kids

Confident Kids

Although nobody gets a parenting manual or bible in the delivery room, it is our duty as parents to try to make our kids as well rounded, happy and confident as possible. It is a lot easier to bring up great kids than it is to try and fix problems caused by bad parenting, when our kids have become adults. Our children are all individuals - they are not our property but people in their own right.

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