One of our previous studies has shown that there are two IgY subclasses (termed IgY1 and IgY2) in the serum of snake Elaphe taeniura, and both subclasses are expressed as full-length and shortened isoforms (IgY1-L, IgY2-L,IgY1-S, and IgY2-S). Using 2-DE and LC-MS/MS, we detected IgY1-L, IgY2-L,IgY1-S, IgY2-S, and the trunction (IgY-T), the LC-MS/MS results showed both IgY1and IgY2 were truncted at N338 of the heavy chain constant region.)