Source:http://linkedlifedata.com/resource/umls/id/C1159084
GO: The formation of peptidyl-dehydroalanine from either peptidyl-tyrosine by phenyl transfer, or from peptidyl-serine, which is coupled with the formation of 5-imidazolinone by the two neighboring residues, produces an 4-methylidene-imidazole-5-one active site of some amino acid ammonia-lyases; the 4-methylidene-imidazole-5-one, is formed autocatalytically by cyclization and dehydration of the sequence ASG. [RESID:AA0181]