Changes in the protein spectrum of the chick embryo mesonephros and metanephros in the course of development.

The protein spectra of two fractions (the soluble and the membrane fraction) of chick embryo kidney homogenates were isolated by electrophoresis on polyacrylamide gels with the aim of detecting the kidney differentiation process at the molecular level and, at the same time, of evaluating similarities in the construction of the mesonephros and metanephros at this level. Corresponding stages of the above two types of kidney were chosen for studying changes in protein structure during differentiation--i.e. the outset of differentiation (the 6-day mesonephros, the 11-day metanephros) and the stage of full maturity (the 14-day mesonephros, the 20-day metanephros). A total of 36 proteins was distinguished. The analysis of the protein spectra showed that the number of proteins changes but slightly during differentiation; the protein composition of the two types of kidney during differentiation altered by 20-35% of the total number of proteins; the similarity of the protein composition of the corresponding stages of mesonephros and metanephros, expressed as the proportion of the number of identical proteins, was greater than the mutual similarity of different developmental stages of the same type of kidney. The percentage of different proteins at corresponding stages of the kidneys varied from 5% to 23% of the total number of proteins detected.