Assertion: protein's acid | /r/PartOf | the a2 beta-casein
Facets:
Source sentences:
text: A1 and A2 beta-casein are genetic variants of the beta-casein milk protein that differ by one amino acid; a proline occurs at position 67 in the chain of amino acids that make up the A2 beta-casein, while in A1 beta-casein a histidine occurs at that position.