O-glycosylated. O-glycosylation on Ser-87 is prevalent in head and neck cancer patients. O-Glycosylation on Ser-330 has a 5 times prevalence in head and neck cancers. Proteolytically cleaved at the tripeptide Xaa-Pro-Gln, where Xaa in the P(3) position is mostly lysine. The endoprotease may be of microbial origin. Pyroglutamate formation occurs on terminal Gln residues of cleaved peptides. Besides on the N-terminal of mature PBR1, pyroglutamate formation found on at least Gln-58. The number of repeats is polymorphic and varies among different alleles. The sequence shown is that of allele L (long). There are allele M (medium) and allele S (short) which contain 12 and 9 approximate tandem repeats repectively.