Histone variants play important roles in chromatin function in mammalian cells. Which one of the following statements is correct in the context of the histone variants?
1
Histone variants have been reported for H3 and H4 but not for H2A and H2B
2
Histone variants have been reported for H3, H4, H2A but not for H2B
3
Histone variants have been reported for H3, H4, H2B but not for H2A
4
Histone variants have been reported for H3, H4, H2A and H2B