Question 247

Question:

A specific congenital form of deafness results from mutation of a sequence of connexin 26 that encodes the channel within the connexon of the gap junction. This mutation is most likely to affect which of the following domains of the protein?

Correct Answer: E.  Transmembrane region

A connexon is an assembly of 6 proteins (called connexins) that forms a gap junction in the (E) transmembrane region between the cytoplasm of two adjacent cells. The connexon is actually the hemichannel supplied by a cell on one side of the junction; two connexons from opposing cells normally come together to form the complete intercellular gap junction channel. However, in some cells, the hemichannel itself is active as a conduit between the cytoplasm and the extracellular space.