A first genotyping assay of French cattle breeds based on a new allele of the <it>extension </it>gene encoding the melanocortin-1 receptor (Mc1r)
2000
Julien Raymond | Levéziel Hubert | Ménissier François | Amigues Yves | Goulemot-Leger Valérie | Delourme Didier | Gallet Paul | Martin Juliette | Rouzaud François | Oulmouden Ahmad
<p>Abstract</p> <p>The seven transmembrane domain melanocortin-1 receptor (Mc1r) encoded by the coat color <it>extension </it>gene (<it>E</it>) plays a key role in the signaling pathway of melanin synthesis. Upon the binding of agonist (melanocortin hormone, <it>α</it>-MSH) or antagonist (Agouti protein) ligands, the melanosomal synthesis of eumelanin and/or phaeomelanin pigments is stimulated or inhibited, respectively. Different alleles of the <it>extension </it>gene were cloned from unrelated animals belonging to French cattle breeds and sequenced. The wild type <it>E </it>allele was mainly present in Normande cattle, the dominant <it>E</it><sup>D </sup>allele in animals with black color (<it>i.e</it>. Holstein), whereas the recessive <it>e </it>allele was identified in homozygous animals exhibiting a more or less strong red coat color (Blonde d'Aquitaine, Charolaise, Limousine and Salers). A new allele, named <it>E</it><sup>1</sup>, was found in either homozygous (<it>E</it><sup>1</sup>/<it>E</it><sup>1</sup>) or heterozygous (<it>E</it><sup>1</sup>/<it>E</it>) individuals in Aubrac and Gasconne breeds. This allele displayed a 4 amino acid duplication (12 nucleotides) located within the third cytoplasmic loop of the receptor, a region known to interact with G proteins. A first genotyping assay of the main French cattle breeds is described based on these four <it>extension </it>alleles.</p>
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