extracellular domain (ECD) found in lymphocyte antigen 6K (Ly-6K) and similar proteins
Ly-6K is required for sperm migration into the oviduct and male fertility by controlling binding of sperm to zona pellucida. It may play a role in cell growth. Ly-6K contains an extracellular domain (ECD) which belongs to Ly-6 antigen/uPA receptor-like (LU) superfamily and exhibits a snake toxin-like fold (also known as three-finger toxin/3FTx fold or three-fingered protein/TFP domain fold).