背景资料：Ubiquitination is an important mechanism through which three classes of enzymes act in concert to target short-lived or abnormal proteins for destruction. The three classes of enzymes involved in ubiquitination are the ubiquitin-activating enzymes (E1s), the ubiquitin-conjugating enzymes (E2s) and the ubiquitin-protein ligases (E3s). MARCH2 (membrane-associated ring finger (C3HC4) 2), also known as RNF172 or HSPC240, is a 246 amino acid multi-pass membrane protein that localizes to the endoplasmic reticulum and contains one RING-CH-type zinc finger. Expressed in a variety of tissues, MARCH2 functions as an E3 ubiquitin-protein ligase that is thought to mediate the ubiquitination and subsequent degradation of CD71 and B7-2 and may be involved in endosomal protein trafficking.