Channel proteins that form a narrow passageway in gap junctions are known as which of the following

Channel proteins that form a narrow passageway in gap junctions are known as connexons

Connexons are assemblies of six proteins that form a pore or a narrow passageway between the cytoplasm of two adjacent cells.
These passageways allow the bidirectional passage of iron and signals between the cells. 

Channel proteins which form a narrow passageway in the gap junctions are known as CONNEXONS.
Connexons are usually found at gap junctions, they form passage way which allow small molecules and ions to pas from cell to cell. Gap junctions are typically found in epithelial cells where the movement of ions facilitate coordinated functions.