Evolution of the androgen receptor

The AR is an evolutionary well-conserved protein. Amino acid homology between the human and mouse, rat and frog ARs, respectively, are 88,85 and 81% (He etal. 1990). It is assumed that the nuclear receptors evolved from a common ancestor by gene duplications (Amero et al. 1992). The rate of amino acid replacement during evolution was very different for the different AR domains. Replacement rates per amino acids position per billion years were calculated for the human and Xenopus laevis receptors to range from 0.04 for the DNA-binding domain or 0.19 for the ligand-binding domain to 1.25 for the N-terminal domain with an overall rate of 0.69 (Thornton and Kelley 1998). Comparative analysis of all available AR sequences and other steroid receptor sequences allowed the identification of residues that are strictly conserved and specific for AR receptors (Thornton and Kelley 1998). These are clustered in specific regions, e.g. the regions immediately prior to and after the DNA-binding domain, the DNA-binding domain itself and a few regions in the ligand-binding domain (Thornton and Kelley 1998).

The structural organization of the AR gene was studied in detail in the human, the mouse and the rat. In these three species there is no essential difference (Baarends et al. 1990; Tilley et al. 1990a; Faber et al. 1993; Lindzey et al. 1993; Grossmann etal. 1994a; 1994b; Kumar etal. 1994;Mizokami etal. 1994; Grossmann and Tindall 1995).

Hair Loss Prevention

Hair Loss Prevention

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