Il polimorfismo del gene MUC1: analisi comparata negli ovi-caprini

Goat and sheep MUC1 exon 2 partial sequencies were aligned and compared in order to analyse the minisatellite repetitive region which is a typical feature of this gene. Repetitive units were identified and their average homology with the consensus sequence was calculated for both species. The primary structure of the corresponding polype ptides was then deduced. The goat repetitive regionis hypervariable (15 different alleles containing 25 to 45 units) and the repetitions are well conserved (93% homology). On the contrary, only 4 alleles with 19 to 22 units have been found in sheep sharing 86% homology, therefore the sheep MUC1 minisatellite region shows lowe r variation than the goat ho mologue. Relationship among mutation frequency, repetitive unit homology, and repetitive regi on size seems to be recognizable. Alignment of goat, sheep, and bovine consensus sequences emphasizes high homology (3- base difference between bovine and goat, 1-base between bovine and sheep, and 2-base between sheep and goat). The corresponding aminoacid sequences are identical. In Ruminants, the repetitive region is specially rich in pote ntial glycosylation with sites serine and threonine residues amounting to 35% of the whole repetive sequence. The findings of our investigations demonstrate that Ruminants may be a useful model to study the mechanisms by which the variation in number of units and in extracellular domain size can modulate the effectiveness of MUC1 protein as a epithelial surface shield.