Lipocalin/cytosolic fatty-acid binding protein domain Proteins which transport small hydrophobic molecules such as steroids, bilins, retinoids, and lipids share limitedregions of sequence homology and a common tertiary structure architecture [<cite idref="PUB00001491"/>, <cite idref="PUB00004787"/>, <cite idref="PUB00004981"/>,<cite idref="PUB00005013"/>, <cite idref="PUB00005340"/>]. This is an eight stranded antiparallel beta-barrel with a repeated + 1 topology enclosinga internal ligand binding site [<cite idref="PUB00005013"/>, <cite idref="PUB00004981"/>]. The name 'lipocalin' has been proposed [<cite idref="PUB00001491"/>] forthis protein family, but cytosolic fatty-acid binding proteins are also included. The sequences of most members of the family, the core or kernal lipocalins, are characterised bythree short conserved stretches of residues, while others, the outlier lipocalin group, share only one or two of these[<cite idref="PUB00000205"/>, <cite idref="PUB00005013"/>]. Proteins known to belong to this family include alpha-1-microglobulin (protein HC);alpha-1-acid glycoprotein (orosomucoid) [<cite idref="PUB00004508"/>]; aphrodisin; apolipoprotein D; beta-lactoglobulin; complementcomponent C8 gamma chain [<cite idref="PUB00003778"/>]; crustacyanin [<cite idref="PUB00001391"/>]; epididymal-retinoic acid binding protein(E-RABP) [<cite idref="PUB00005238"/>]; insectacyanin; odorant-binding protein (OBP); human pregnancy-associated endometrial alpha-2globulin; probasin (PB), a rat prostatic protein; prostaglandin D synthase (<db_xref db="EC" dbkey="5.3.99.2"/>) [<cite idref="PUB00005379"/>]; purpurin; VonEbner's gland protein (VEGP) [<cite idref="PUB00001451"/>]; and lizard epididymal secretory protein IV (LESP IV) [<cite idref="PUB00002777"/>].