Early endosomes are cellular compartments that receive endocytosed materials and sort them for vesicular transport to late endosomes and lysosomes, as well as for recycling material to the plasma membrane. Early endosome antigen 1 (EEA1) is an early endosomal protein that contains an N-terminal zinc finger motif, a cys-rich C-terminal metal-binding finger, and multiple sites for N-glycosylation, phosphorylation, and N-myristoylation. Expression of EEA1 mRNA is observed in skeletal muscle, heart, brain, lung, liver, and pancreas. Immunoblot analysis shows that EEA1 is a 180-kDa protein localized in membrane and cytosolic fractions. Immunofluorescence microscopy shows that EEA1 colocalizes with transferrin and with RAB5 in early endosomes, but not with RAB7 in late endosomes.
