Figure 2. Variation in the sic gene and Sic protein identified in M1 group A Streptococcus isolates characterized in the study. The figure is a compilation of variations found in the 15 distinct sic alleles in the sample. The numbers at the top of the figure refer to the nucleotide sequence position of a sic allele described in reference 6. Single-letter amino acid abbreviations are used. SRR, amino-terminal short repeat region; Roman numeral, short repeats I-V which recur in SRR; R2 and R3, tandem repeats; MGAS strain, Musser Group A Streptococcus strain number; X, presence of polymorphism.