Distribution of PoLV1-4 motifs in DBL1α from gDNA. The 71 sequences were classified in six sequence groups based on the number of cysteine residues within the tag region and a set of sequence motifs at four positions of limited variability (PoLV 1–4). This classification is referred to as cysteine/PoLV sequence grouping . In each group, one major motif was found, i.e. LYLG in PoLV1, LRED in PoLV2, KAIT in PoLV3 and PTYF in PoLV4.