Quantitative mass spectrometry analysis of histone H3 modifications of BPV1 virions and bovine keratinocytes. (A) Relative abundance of the H3 histone acetylation and methylation in histones extracted from BPV1 virions (BPV1, red), proliferating bovine epidermal keratinocytes (BEK grow, dark blue), partially differentiated bovine epidermal keratinocytes (BEK Ca++, blue), or fully differentiated bovine epidermal keratinocytes grown as organotypic skin equivalents (BEK raft, light blue). The peptide sequences are as follows: TKQTAR, aa 3 to 8; KSTGGKAPR, aa 9 to 17; KQLATKAAR, aa 18 to 26; KSAPATGGVKKPHR, H3.1 aa 27 to 40; KSAPSTGGVKKPHR, H3.3 aa 27 to 0. Abundances are calculated as a percentage of total modified and unmodified peptides based on integrated peak areas. n = 3. Error = SD. (B) The proportion of modification of each residue was calculated for BPV1 (average, n = 3) and bovine cell samples (average of all three control cell conditions, n = 9) from the data in panel A and Table S2.