Figure 3
Organization of the ST proteins. (A) The signal peptide, the mature N-terminal end before repeats and the tandem repeat region are shown. (B) Detail of amino acid sequence of the N-terminal end of the mature protein. (C, D) Details of the tandem repeat oligopeptides represented using WebLogo. (C) Comparison of ST protein repeats having different sizes, showing the conserved consensus sequence DFEPRPX4Y. (D) Comparison of the most abundant ST protein repeats having 25 and 26 amino acids. The general consensus sequence for each repeat is DFEPRPX4YX6-7KXKKXFXK, which shows a less conserved K at positions 19, 21, 22 and 26 (26 amino acids repeats) or 18, 20, 21 and 25 (25 amino acids repeats). Apart from X4 positions, amino acids X6-7 in the consensus pattern are phylogenetically conserved, being rich in D and N. The WebLogo consists of stacks of symbols: one stack for each position in the sequence. The overall height of the stack indicates the sequence conservation at that position, while the height of the symbols within the stack indicates the relative frequency of each amino acid at that position. Amino acids are coloured according to their chemical properties: polar amino acids (G,S,T,Y,C,Q,N) are in green; basic (K,R,H) in blue; acidic (D,E) in red, and hydrophobic (A,V,L,I,W,F,M) amino acids are in black. Bit: measure of conservation at a particular sequence position; the maximum conservation for a given amino acid in a sequence is 4.32 bits.