Assertion: histidine | /r/AtLocation | that position
Facets:
value: in a1 beta-casein
type: LOCATION
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.