Here, the role of yeast soluble cytosolic proteins in lysine tRNA import into mitochondria is described and discussed. This topic was studied for many years in the group of Dr. Ivan Tarassov (University of Strasbourg, France) in collaboration with the group of Prof. Igor A. Krasheninnikov (Moscow State University, Russia). As a result, three soluble proteins were identified as "tRNA import factors". For each of them, the mechanisms of involvement into tRNA import process were outlined. For the moment, the chain of events that the tRNA undergoes in the cytoplasm prior to its mitochondrial import is more or less clear. This chain of events is described in detail in this book.