From this article https://ui.adsabs.harvard.edu/abs/2005Sci...308.1909S/abstract
“We created transgenic mice that overexpress human catalase localized in the peroxisome, nucleus, or mitochondria (MCAT).”
How exactly do such changes occur step by step? Those. how did they find which genes needed to be changed in order to get the result in overexpression of catalase and in mitochondria?
I am new to biology, and although I understand, for example, how CRISPR works, it’s not clear where people get such data "this gene in the mouse is responsible for the expression of catalase in mitochondria. "Where to find such data?