Well, unlike voltage gated and ligand gate on channels, these gap junctions actually have relatively large pore sizes, so the diameter is about 20 angstroms. On top of that, they also allowed the movement of not only inorganic ions, so ions like calcium, sodium, potassium, chloride ions across that particular channel, but they also allow the movement of organic substances such as glucose molecules, amino acids, as well as nucleotides. So we see, unlike the voltage gated and ligangate on channels, which are usually specific and can only move these inorganic ions, gap junctions are non specific. They allow any molecule to move across or any ion to move across, as long as it's not too large. So large substances such as proteins and polynucleotides and polysaccharides, these molecules cannot pass across gap junctions. Now, unlike these voltage gated and ligand gate on channels, which are only open for about a millisecond before being closed or inactivated, these gap junctions can be open anywhere from seconds to minutes.