TRANSCRIPTION, HUMAN CHROMOBOX HOMOLOG 2, CBX2, H3K27, STRUCTURAL GENOMICS, STRUCTURAL GENOMICS CONSORTIUM, SGC, ALTERNATIVE SPLICING, CHROMATIN REGULATOR, DNA-BINDING, NUCLEUS, REPRESSOR, TRANSCRIPTION REGULATION CRYSTAL STRUCTURE OF THE COMPLEX OF HUMAN CHROMOBOX HOMOLOG 2 (CBX2) AND H3K27 PEPTIDE 3H91