Schematic representations of the effects of the Histidine > Proline (PLCζH398P) (A) and Histidine > Leucine (PLCζH233L) (B) point mutations identified by Heytens et al . (2009) and Kashir et al . (2012) in an infertile male patient diagnosed with oocyte activation deficiency. For both A) and B), schematics represent local protein folding before mutation (i) and after mutation (ii). C) Microinjection of wild type and mutant PLCζ into mouse oocytes and resulting calcium release patterns. FI 340/380: ratio of fluorescence at wavelengths of 340 nm and 380 nm. Reproduced from Heytens et al. (2009) and Kashir et al. (2012) with permission.