In mammals, GRIFIN (galectin related inter fibre protein) is a lens crystallin protein that does not bind beta-galactoside sugars and has atypical sequences at normally conserved regions of the carbohydrate-binding domain []. It binds to alpha-crystallin in the lens []. Unlike the mammalian homologue, fish GRIFIN contains all amino acids critical for binding to carbohydrate ligands and its carbohydrate-binding properties have been confirmed. Fish GRIFIN may also function as a crystallin [].
Galectin relatives such as lens crystalline protein GRIFIN and the galectin-related protein HSPC159, have been identified. They are characterised by significant sequence deviations at the most critical residues for carbohydrate-binding, leading to lack of beta-galactosides binding activity.Galectin-related protein (GRP), previously known as HSPC159, does not bind lactose, and may not bind carbohydrates. Its function remains unclear [, ].
