Complex sentence: PRDM9 specifically trimethylates'Lys-4' of histone H3 during meiotic prophase and is essential for proper meiotic progression, but does not have the ability to mono-and dimethylate'Lys-4' of histone H3.
Split into simpler sentences: PRDM9 specifically trimethylates'Lys-4' of histone H3 during meiotic prophase and is essential for proper meiotic progression. Does not have the ability to mono-and dimethylate'Lys-4' of histone H3.