Plot color coded grid and barplot on same axes?

I have a table with three columns: The first one has a single letter for each row (it's a protein amino acid sequence). The second has a number, and the third has one of three letter values (corresponding to a class prediction).

I want to plot this data such that the x-axis is the sequence of letters (col 1), then the numerical values are plotted as a bar plot with a bar for each letter, and then the class prediction is plotted as a color-coded bar (different rectangles colored based on class).

Pretty much what's in this image, with the purple thing for col2 data, and one of the boxy things for col3 data, but also with the letters plotted on the x-axis.