BRO1 Domain And CAAX Motif Containing Protein (BROX)

Human Brox is a newly identified 46 kDa protein that has a Bro1 domain-like sequence and a C-terminal thioester-linkage site of isoprenoid lipid. Mammalian Alix and its yeast ortholog, Bro1, are known to associate with charged multivesicular body protein 4 (CHMP4), a component of endosomal sorting complex required for transport III, via their Bro1 domains and to play roles in sorting of ubiquitinated cargoes.Fluorescent signals of monomeric green fluorescent protein (mGFP)-fused Brox(WT) merged partly with those of Golgi markers and with those of abnormal endosomes induced by overexpression of a dominant negative mutant of AAA type ATPase SKD1/Vps4B in HeLa cells, but such colocalization was less efficient for mGFP-Brox. A physiological significance of farnesylation of Brox in its subcellular distribution and efficient interaction with CHMP4s in vivo.