Hong Young Seok, Park Soyeon, Geng Chaoxian, Baek Kwanghee, Bowman John D, Yoon Jaeseung, Pak William L
Department of Biological Sciences, Purdue University, 1392 Lilly Hall, West Lafayette, IN 47907, USA.
J Biol Chem. 2002 Sep 13;277(37):33884-9. doi: 10.1074/jbc.M204075200. Epub 2002 Jul 9.
The trp gene encodes subunits of a highly Ca(2+)-permeable class of light-activated channels of Drosophila photoreceptors. The recently characterized mutation in this gene, Trp(P365), is semidominant and causes massive degeneration of photoreceptors by making the TRP channel constitutively active. We show that a single amino acid change, Phe-550 to Ile, near the beginning of the fifth transmembrane domain of TRP channel subunits is necessary to induce, and sufficient to closely mimic, the original mutant phenotypes of Trp(P365). Hypotheses are presented as to why the amino acid residues at position 550 and its immediate vicinity might be important in influencing the regulation of the TRP channel and why the substitution of Phe for Ile at this position, in particular, could result in constitutive activity of the channel.
