Change of Cytochrome c Structure during Development of the Mouse

Abstract

The structure of cytochrome c during mouse development is investigated. For this purpose the amino acid sequence of cytochrome c of the adult mouse had to be determined. The structure of cytochrome c of adult differentiated mouse cells differs in two amino acid residues from the known amino acid sequence of rabbit cytochrome c. No indication of different forms of cytochrome c in the adult differentiated cells was obtained. The structure of cytochrome c from 11.5‐day‐old mouse embryos is identical with that of adult mouse tissues. Since germ cells after meiotic division are the immediate precursors of a new individual, the structure of cytochrome c from sperm‐containing mice testes was investigated. By means of chromatography of the cytochrome c and of peptide maps and amino acid analyses of its tryptic peptides, it is shown that mouse testis contains two isocytochromes c in about equal amount. The structure of one of these two isocytochromes c is identical with the structure of the adult‐type cytochrome c of mouse. The testis‐specific cytochrome c, which is assumed to be located in the sperm cells, differs in 13 of its 104 amino acid residues from the adult‐type cytochrome c. From comparison of the primary and the spatial structures of the adult‐type and the sperm‐type isocytochromes c with the known structures of cytochrome c of more than 65 different species it is concluded that the duplication of the cytochrome c structural gene, causing the existence of the two ontogenetic‐specific isocytochromes c in mouse, has occurred early in the evolution of eucaryotes.

Assembly of Cytochrome c. Apocytochrome c Is Bound to Specific Sites on Mitochondria before Its Conversion to Holocytochrome c

“…Samples were incubated for 4 h at 37 'C and then dried in vucuo. They were applied onto thin-layer plates (10 x 10 cm) of microcrystalline cellulose (G 1440, Schleicher & Schiill, Dassel) and subjected to two-dimensional separation [42] : First, electrophoresis was performed in 10 % pyridine acetate p H 4.7 at -10 "C for 30 min. Then chromatography was performed in the second dimension using 1 -butanol/HzO/ pyridine/acetic acid (75/60/50/15) for 1 h. The dried plates mapping the radioactively labelled peptides were sprayed with 0.4 % 2.5-diphenyloxazole in 90 % 2-mcthylnaphthalcne, 10 % toluene in order to enhance autoradiographic sensitivity [43] and then they were laid onto X-ray film (Curix RP 1, Agfa-Gevaert) for 3 days at -80 'C.…”

Processed pseudogenes for rat cytochrome c are preferentially derived from one of three alternate mRNAs.

“…In contrast, the somatic cells of higher organisms are generally known to possess only a single form of cytochrome c polypeptide (17,31). The only bona fide genetic variant found in higher eucaryotes is the mouse testis cytochrome c, which differs from the adult form in 13 of 104 amino acid residues (10).…”

Both upstream and intron sequence elements are required for elevated expression of the rat somatic cytochrome c gene in COS-1 cells.

“…One mammalian isoform of cytochrome c is expressed in somatic tissues, and a second is expressed during spermatogenic differentiation (14). The rat somatic cytochrome c gene has introns dividing its 5' noncoding and coding regions and directs the synthesis of 1,400-, 1,100-, and 700-nucleotide mRNAs (32,36).…”