Steroid binding sites

A. Orstan, M. F. Lulka, B. Eide, P. H. Petra, and J. B. A. Ross, The steroid-binding site of human and rabbit sex steroid-binding protein of plasma Fluorescence characterization with... 

Conseil, G. et al., Flavonoids a class of modulators with bifunctional interactions at ATP- and steroid-binding sites on mouse P-glycoprotein, Proc. Natl. Acad. Sci. USA, 95, 9831, 1998. 

Figure 4.12 The GABA-A channel functions as a receptor for many multiple different drug classes, including benzodiazepines (e.g., diazepam) and barbiturates (e.g., phenobarbital). There is also a steroid-binding site on the GABA-A channel which may be useful in the future design of general anesthetics.

Representative Examples of Affinity Reagents Directed Towards Steroid-Binding Sites... 

Schrukter, J., Gopalaswamy R. and Crippen, G.M. (1997) Objective models for steroid binding sites ofhuman globulins. /. Comput. Aid. Mol. Des., 11, 93-110. 

J -3-Keto isomerase catalyzes the isomerization of J -3-ketosteroids to zl -3-ketosteroids by stereospecific transfer of a hydrogen atom from C(4) to C(6). There is considerable evidence that it is the 40- and 6/5-hydrogens that are involved and that the reaction proceeds via an enolic intermediate. A low resolution (6 A) crystal structure determination has been published and the probable steroid-binding site identified via a bound inhibitor, 4-acetoxy-mercuric estradiol. The results of a higher resolution study (2.5 A) combined with the results of NMR studies and analysis of activity of mutant forms of the enzyme have helped to further define the probable active site of the enzyme [64]. 

The isomerase enzyme is an elongated dimer in which the proposed steroid binding site is surrounded by a distorted barrel of eight 0 strands and a single a helix. Six 0 strands and the a helix are from one monomer, and two strands are contributed from the second. The dimer interface is made up of the meeting of the barrel heads. While there are two similar shaped barrels in the dimer only one appears to contain the substrate, with one end of the steroid at the surface of the barrel top (Figure 14.16). 

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