FKBPs define a subfamily of peptidyl-prolyl cis/trans isomerases (PPlases). PPlases are known to play roles in cellular protein folding, protein interactions and signal transduction. Here we describe NcFKBP22 from Neurospora crassa, a novel type of FKBP. NcFKBP22 is synthesized as a precursor protein with a cleavable signal sequence. In addition to a typical FKBP domain in the amino-terminal part mature NcFKBP22 contains a novel second domain which is unique amongst all known FKBPs. The amino acid composition of this carboxyterminal domain is highly biased. Secondary structure predictions suggest that this domain may form an amphipathic alpha-helix. The carboxy-terminus of NcFKBP22 is -HNEL, a potential endoplasmic reticulum (ER) retention signal, suggesting that NcFKBP22 is a resident protein of the ER.