Functional expression of the new gap junction gene connexin47 transcribed in mouse brain and spinal cord neurons

A new mouse gap junction gene that codes for a protein of 46,551 Da has bee n identified and designated connexin47 (Cx47). It mapped as a single-copy g ene to mouse chromosome 11. In human HeLa cells and Xenopus oocytes, expres sion of mouse Cx47 or a fusion protein of Cx47 and enhanced green fluoresce nt protein induced intercellular channels that displayed strong sensitivity to transjunctional voltage. Tracer injections in Cx47-transfected HeLa cel ls revealed intercellular diffusion of neurobiotin, Lucifer yellow, and 4', 6-diamidino-2-phenylindole. Recordings of single channels yielded a unitary conductance of 55 pS main state and 8 pS substate. Cx47 mRNA expression wa s high in spinal cord and brain but was not found in retina, liver, heart, and lung. A low level of Cx47 expression was detected in ovaries. In situ h ybridizations demonstrated high expression in a motor neurons of the spinal cord, pyramidal cells of the cortex and hippocampus, granular and molecula r layers of the dentate gyrus, and Purkinje cells of the cerebellum as well as several nuclei of the brainstem. This expression pattern is distinct fr om, although partially overlapping with, that of the neuronally expressed c onnexin36 gene. Thus, electrical synapses in adult mammalian brain are like ly to consist of different connexin proteins depending on the neuronal subt ype.