Structural organization of genes coding for GH44 CDs, excluding GH44 members with only a signal peptide and a CD. The gene encoding O. terrae's GH44 member produces a 920-residue protein whose domain structure is unclassified. The sequence was searched against the Pfam library, and a low E-value, 1.22 × 10−22, was found for a PKD (polycystic kidney disease)-type domain. Ig, immunoglobulin.