Molecular insights into PRL and PRLR genes' influence on milk obtaining – a review

The prolactin (PRL) gene, mapped on chromosome 23 in cattle, is usually considered in association studies with various milk traits. Although contradictory results of genotypes associations can be reported, they are generally justified if taking into account the variability of individuals (differences in investigated breeds), the number of individuals, and the investigated milk trait. The PRL gene is not a part of any Quantitative Trait Locus (QTL), but the gene of its receptor (PRLR) is. This fact is important, considering the role of PRLR protein in some steps of PRL action. This study is a review that debates important and up-dated aspects of PRL and PRLR genes' location and structure, physiological mechanisms of action of PRL hormone, and some associations of a well-studied polymorphism (a point mutation) with some milk traits.