passages.id: split_8_test_1514_passage
passages.type: progene_text
passages.text: The 19 - exon MCCA gene maps to 3q25-27 and encodes a 725 - residue protein with a biotin attachment site ; the 17-exon MCCB gene maps to 5q12 - q13 and encodes a 563 - residue polypeptide .