By auxin. The cytochrome b5 heme-binding domain lacks one of the conserved iron-binding His residues at position 100. Belongs to the cytochrome b5 family. MAPR subfamily. The predicted gene At4g14950 has been split into 2 genes: At4g14950 and At4g14965. The predicted gene At4g14950 has been split into 2 genes: At4g14950 and At4g14965.