{"id":19590,"date":"2026-06-17T10:09:08","date_gmt":"2026-06-17T08:09:08","guid":{"rendered":"https:\/\/www.nanion.de\/?post_type=resource_library&#038;p=19590"},"modified":"2026-06-17T10:09:08","modified_gmt":"2026-06-17T08:09:08","slug":"2026-blue-versus-green-absorbing-anion-channelrhodopsins-essential-tools-in-optogenetics-differ-fundamentally-in-gating-mechanisms","status":"publish","type":"resource_library","link":"https:\/\/nanion.com\/ja\/resource_library\/2026-blue-versus-green-absorbing-anion-channelrhodopsins-essential-tools-in-optogenetics-differ-fundamentally-in-gating-mechanisms\/","title":{"rendered":"2026 &#8211; Blue- versus green-absorbing anion channelrhodopsins, essential tools in optogenetics, differ fundamentally in gating mechanisms"},"content":{"rendered":"<p>The genomes of many protists encode at least one pair of spectrally distinct cation or anion channelrhodopsins. Two cation channelrhodopsins (CCRs) initiate different transduction cascades in\u00a0<i>Chlamydomonas<\/i>. Two\u00a0<i>Guillardia<\/i>\u00a0anion channelrhodopsins (ACRs) are emerging molecular tools for optical inhibition of neuronal firing, but their functions in the source organism remain unclear. Furthermore,\u00a0<i>Gt<\/i>ACR2 remains poorly investigated compared to\u00a0<i>Gt<\/i>ACR1, although its faster channel kinetics makes it preferable for optogenetic control of neurons firing at high frequencies. Using patch-clamp recording in mammalian cells, photochemical characterization of purified proteins, and mutational analysis, we found a fundamental mechanistic difference between blue-absorbing\u00a0<i>Gt<\/i>ACR2 and green-absorbing\u00a0<i>Gt<\/i>ACR1, which may indicate different functions in the alga.\u00a0<i>Gt<\/i>ACR2 exhibits only one channel gating mechanism, unlike\u00a0<i>Gt<\/i>ACR1, in which we had detected two mechanisms.\u00a0<i>Gt<\/i>ACR2\u2019s faster channel closing strongly depends on the holding voltage, and its photocycle shows considerable intermediate reversibility. Photocurrents evoked by continuous light pulses reflecting secondary photochemistry reveal further differences between\u00a0<i>Gt<\/i>ACR1 and\u00a0<i>Gt<\/i>ACR2. Mutagenetic replacement of five divergent\u00a0<i>Gt<\/i>ACR2 residues with those of\u00a0<i>Gt<\/i>ACR1 reproduced the latter\u2019s spectral sensitivity and slow biphasic channel closing. Only one\u00a0<i>Gt<\/i>ACR2 mutation, R129C, which individually caused the most substantial red shift, restored the gating mechanism typical of\u00a0<i>Gt<\/i>ACR1.\u00a0<i>Gt<\/i>ACR2, but not\u00a0<i>Gt<\/i>ACR1, exhibited a change in the F<sup>\u2212<\/sup>\/Cl<sup>\u2212<\/sup>\u00a0relative permeability during the single-turnover photocycle. Comparison to\u00a0<i>Chlamydomonas<\/i>\u00a0CCRs and ACRs from other protists suggests that these differences between blue- and green-absorbing ChRs are a general rule, which can guide further development of optogenetic tools.<\/p>\n","protected":false},"featured_media":0,"template":"","products_tags":[42],"resource_type":[75],"application_areas":[50,53],"therapeutic_areas":[143],"target_categories":[338],"target_families":[369],"targets":[275],"resource_keyword":[],"class_list":["post-19590","resource_library","type-resource_library","status-publish","hentry","products_tags-syncropatch-384","resource_type-publication","application_areas-ion-channels","application_areas-assay-development-and-validation","therapeutic_areas-assay-development-and-validation","target_categories-other-ion-channels","target_families-light-driven","targets-channelrhodopsin"],"acf":[],"_links":{"self":[{"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/resource_library\/19590","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/resource_library"}],"about":[{"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/types\/resource_library"}],"wp:attachment":[{"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/media?parent=19590"}],"wp:term":[{"taxonomy":"products_tags","embeddable":true,"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/products_tags?post=19590"},{"taxonomy":"resource_type","embeddable":true,"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/resource_type?post=19590"},{"taxonomy":"application_areas","embeddable":true,"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/application_areas?post=19590"},{"taxonomy":"therapeutic_areas","embeddable":true,"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/therapeutic_areas?post=19590"},{"taxonomy":"target_categories","embeddable":true,"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/target_categories?post=19590"},{"taxonomy":"target_families","embeddable":true,"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/target_families?post=19590"},{"taxonomy":"targets","embeddable":true,"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/targets?post=19590"},{"taxonomy":"resource_keyword","embeddable":true,"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/resource_keyword?post=19590"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}