title: Evidence for an ancestral immunoglobulin gene coding for half a domain.
mesh_terms: D000595:Amino Acid Sequence; D005075:Biological Evolution; D003553:Cystine; D005796:Genes; D005815:Genetic Code; D007136:Immunoglobulins / Q000032:analysis
chemical_list: D007136:Immunoglobulins; D003553:Cystine