Exon 2 codes for amino acids 28-82, which include the catalytically active residues and a cluster of amino acids which bind rings C, D, E, and F of the oligosaccharide substrate.

• 外显子2为氨基酸28-82编码，其包括催化中心的残基（Glu35和Asp53）和结合寡糖底物的一簇氨基酸。外显子2可能代表原始的糖苷酶。