Sperm nuclear protein analysis. A representative acid-urea gel separation of nuclear proteins extracted from epididymal sperm and testes of 9/10NPYq- mutant (M, n = 4) and XYTdym1Sry control (C, n = 3) mice. (a) Coomassie blue stained gel. (b) Immunoblot with Hub2B antibody recognizing P2. (c) Immunoblot with preP2 antibody recognizing preP2. P1 and P2, protamine 1 and 2, respectively; PreP2, premature forms of protamine 2.