New modified forms of the nuclear Vitamin D receptor, useful e.g. to screen for therapeutic Vitamin D agonists and antagonists, lack the flexible insertion domain

摘要

Polypeptides (I), derived from the nuclear Vitamin D receptor (VDR) of humans or other animals, in which the flexible insertion domain (FID) within the receptor's ligand binding domain (LBD) is modified by substitution or deletion of amino acids, are new. New polypeptides (I), derived from the nuclear Vitamin D receptor (VDR) of humans or other animals, in which the flexible insertion domain (FID) within the receptor's ligand binding domain (LBD) is modified by substitution or deletion of at least 30 (preferably 40, and up to all) amino acids (aa) and optionally one or more (up to all) of the aa in region 1-125 (especially 1-117 or 123) of the VDR are substituted or deleted retain the ligand-binding and transactivation properties of LBD, are stable (i.e. can be stored), particularly in pH 7 0.1M sodium chloride solution for at least a week without loss of properties (contrast unmodified LBD), can be crystallized in aqueous solution, especially at 4 deg C by the hanging drop vapor-diffusion method and are soluble in aqueous solution. Independent claims are also included for the following: (1) crystals comprising (I), optionally in association with Vitamin D, or its (ant)agonistic analog; (2) nucleic acid (II) that encodes (I); (3) recombinant nucleic acid (IIa) comprising (II) and elements required for transcription, particularly promoter and terminator; (4) vector, especially a plasmid, containing (II) or (IIa); (5) host cell transformed with the vector of (4); (6) preparation of (I) by culturing cells of (5); (7) method of screening for Vitamin D analogs; and (8) method for analyzing the three-dimensional (3D) structure of complexes between (I), or the crystals of (1), and another molecule.