| Abstract: | The secondary structure of seven hormones of the prolactin family was predicted by two known prediction algorithms with the following averaging of the results for the whole homologous group of proteins. It was shown that the mentioned hormones are related to the alpha-helical type of protein molecules. The comparative analysis of the prolactin family and the kindred growth hormone family has been carried out on different levels of their structural organization. A conclusion is drawn, that despite the significant differences in the primary structures and small differences in the secondary structures, the three-dimensional structure for the prolactin molecules and the growth hormone are very similar and repeat in the same way the packing of alpha-helices. The study of the relationship of the prolactin structure and function has been carried out. The regions of the amino acid sequence, able to form prolactin antigenic sites and conditionally incorporated into two highly specific spatial groups were revealed. The region of the primary structure 80-137 determining lactogenic and proliferational function of the molecule and forming the alpha-hairpin in the tertiary structure has been discovered. The structural particuliarity of one of the binding sites of prolactin and human growth hormone with lactogenic receptor was reveal. An explanation for the absence of lactogenic activity in all kinds of growth hormones except human ones has been proposed. |
