Secretoglobin

The proteins are mostly alpha-helical, and the dimer is formed in an antiparallel way. The dimer interface features a cavity formed across the two monomers, which can accommodate small to medium sized ligands like steroids and phospholipids. The binding and release may be coupled with the redox state of the cystines, i.e. the presence of these disulfide bonds. Many have regulatory functions. == Classification ==

The family was classified by sequence homology into 6 subfamilies in 2006. The human and mouse genomes only contain the first three families, per a 2011 update. Not every family is monophyletic. Rat prostatein (rat prostatic steroid binding protein) is a three component, tetrameric protein complex built from three lipophilin-like genes in groups 2 and 3. Some sources describe it as the ortholog of lipophilin. Extra computational research confirms the similarity, invalidating subfamilies 4 and 5 fully. == References ==