Multiple choice Which of the following cytochromes is a highly soluble protein? cytochrome a cytochrome b cytochrome c cytochrome d Reveal answer Fill a bubble to check yourself C Correct answer Explanation Cytochrome c is a highly soluble protein.The heme group of cytochrome c accepts electrons from the bc1 complex and transfers electrons to the complex IV. Cytochrome c is also involved in initiation of apoptosis.