Biochemical characterisation of hZP2 from unfertilised and fertilised oocytes. ZP were isolated from a pool of 3 unfertilised (lane 1) and 3 fertilised (lane2) oocytes recovered after an IVF procedure (A) or a sperm-binding experiment (B) (experiment 1, Table 1). Oocytes were cleared of bound spermatozoa before ZP isolation. ZP proteins were then solubilised in Laemmli buffer and separated by SDS-PAGE in a 7% polyacrylamide gel. Glycoproteins were transferred to a PVDF membrane and ZP2 was detected by incubation with anti-rhZP2 and enhanced chemiluminescence. Molecular masses are indicated on the left.