RESUMEN
MUC1 is a transmembrane glycoprotein expressed on the apical surfaces of the uterine epithelial tissue with predicted functions in protection and cell-cell adhesion. These properties are closely related with the repetitive region [variable number of tandem repeats (VNTR)] of the extracellullar domain and with the O-glycosylation in their serine and threonine residues. This study describes a polymerase chain reaction (PCR) protocol to analyse MUC1 bovine genetic polymorphism and demonstrates the existence of a VNTR within the sites for O-glycosylation. Oligonucleotide primers based on the Bos taurus mucin (MUC1) gene sequence GenBank AF399757 were used to amplify five VNTR MUC1 alleles from a study group of 56 pure Nelore bovines. The number of repeats varied between 10 and 24, being more prevalent than the alleles with less number of repeats. The DNA sequence analysis revealed two repeats and one of them presented 100% homology with the bovine consensus sequence already reported. The second repeat showed codons that translate to serine and proline amino acids, which are conserved in the MUC1 of several species. This study is the first description of allelic variation and the VNTR structure in the Nelore breed MUC1 gene, and we suggest that this genetic variability can be tested for association with variation in reproductive traits in Nelore cattle.