This is a follow up to my question posted here Processing proteomics data
In relevance to my research, I've been looking for proteomics data (control vs. diabetic) and I found a dataset in the article "Diabetes causes marked inhibition of mitochondrial metabolism in pancreatic β-cells" (figures from here: link).
I would like to know how to generate the following heat map from the normalized abundances reported.
Heat maps of relative mRNA and protein levels of the indicated genes in islets isolated from control and 2-week diabetic βV59M mice. Each box corresponds to a different animal. Colour indicates log2 fold-change. Heat map: TCA cycle. Red, proteins upregulated in diabetes; blue, proteins downregulated in diabetes. Grey, no change or not detected. PDK1, pyruvate dehydrogenase kinase 1. Abundance: Abundance of the indicated proteins, quantified by mass spectrometry, in islets isolated from control (black, Ctrl, n = 4) and 2-week diabetic βV59M (white, Diab, n = 4) mice.
I am not able to understand how the log2 fold-change is computed from the abundance.
For instance, if we consider
PDK1 (first panel) the abundance measure of control is ~50000 and diabetic is ~200000. Heat map says log2 fold-change (in the figure description added above). What is the fold-change that is referred to? From what is shown, I think this is not diabetic/control fold change; we see two panels (i.e one for control (4 samples) and the other for diabetic (4 samples)) and not a single panel. Since the legend is from (-2 to 2) I think these values are not log2 (abundance) as well.
Could someone please clarify how the heat map has been generated from the abundance measures? Basically, I want to know how to generate the first heatmap figure from abundance plots.