AVIAN CATHEPSIN-B CDNA - SEQUENCE AND DEMONSTRATION THAT MESSENGER-RNAS OF 2 SIZES ARE PRODUCED IN CELL-TYPES PRODUCING LARGE QUANTITIES OFTHE ENZYME

Overlapping cDNA fragments encoding avian cathepsin B were cloned from an osteoclast cDNA library and sequenced. The primary structure of th e prepro enzyme deduced from this sequence has 340 amino acids. The ma ture portion of the enzyme is 80% identical with murine cathepsin B; r egions found in other papain superfamily enzymes are conserved. In ost eoclasts and cultured macrophages, which produce large quantities of c athepsin B, mRNAs of 1.8 and 2.4 kb are produced in approximately equa l quantities, while cells producing smaller quantities of the enzyme p roduce predominantly the 2.4 kb form. This variation in mRNAs suggests transcriptional differences related to production of large quantities of the enzyme.