Fig. 2From: GPCRtm: An amino acid substitution matrix for the transmembrane region of class A G Protein-Coupled ReceptorsBubble chart of the difference matrix obtained by subtracting from GPCRtm the JTTtm (lower) and BLOSUM62 (upper) substitution matrices. Positive and negatives values are showed in grey and white circles respectively. Bubbles are scaled according to the absolute value of the difference (numerical values are available in the supporting data)Back to article page