The differentiation of cEGF into subtype 1 and 2, which probably occurred after its split from hEGF, is based on different residue numbers between the distinct half-cystines. Both hEGF- and cEGF-like domains contain an N-terminal calcium binding region.

Both subtypes display unusual post-translational modifications, including O-glycosylations and ?-hydroxylation of aspartate and asparagine residues. O-fucose modifications have only been detected in hEGF-like domains and they are