Fig 1. The amino acid sequences of catalytic subunits of the PP2A/4/6 phosphoprotein phosphatase complexes in humans and C. elegans are highly homologous.

The frequency of a particular amino acid at equivalent positions within catalytic subunits of the PP2A, PP4, and PP6 complexes in humans was compared to the corresponding subunits in C. elegans. When necessary, N-termini were trimmed by as many as 26 amino acids so that all sequences being compared were of the same length. Amino acids are denoted by their single letter code. The height of each letter corresponds to the frequency with which a particular amino acid is found at a given position, with taller letters indicating greater consensus at that position among the proteins being compared. If only one letter appears at a given position it indicates absolute identity at that position between the proteins. Letters are stacked when different amino acids are found at the equivalent position within the proteins. The color of the letters indicates whether amino acids are hydrophilic (blue), neutral (green) or hydrophobic (black). Red asterisks are placed above amino acids with absolute identity shown to be bound or modified by regulatory proteins TIPRL, PTPA, α4 or LCMT-1 in mammals. The conserved helix switch and loop switch regions are indicated by turquoise and orange bars, respectively.