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3.E.1.8.1
Anion-specific light-gated channel rhodopsin of 438 aas, Acr1, lacking measurable cation transport capability (Govorunova et al. 2015). The crystal structure of the light-gated anion channel, GtACR1, revealed a continuous tunnel traversing the protein from extracellular to intracellular pores (Li et al. 2021). The tunnel is the conductance channel closed by three constrictions: C1 in the extracellular half, mid-membrane C2 containing the photoactive site, and C3 on the cytoplasmic side. The crystal structure of bromide-bound GtACR1 revealed structural changes that relax the C1 and C3 constrictions, including a novel salt-bridge switch mechanism involving C1 and the photoactive site. Thus, substrate binding induces a transition from an inactivated state to a pre-activated state in the dark that facilitates channel opening by reducing free energy in the tunnel constrictions. The results provide direct evidence that the tunnel is the closed form of the channel of GtACR1 and shed light on the light-gated channel activation mechanism (Li et al. 2021).

Accession Number:L1J207
Protein Name:Uncharacterized protein
Length:438
Molecular Weight:49902.00
Species:Guillardia theta CCMP2712 [905079]
Number of TMSs:7
Substrate anions

Cross database links:

Structure:
6CSM   6EDQ     

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Predict TMSs (Predict number of transmembrane segments)
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FASTA formatted sequence
1:	MSSITCDPAI YGEWSRENQF CVEKSLITLD GIKYVQLVMA VVSACQVFFM VTRAPKVPWE 
61:	AIYLPTTEMI TYSLAFTGNG YIRVANGKYL PWARMASWLC TCPIMLGLVS NMALVKYKSI 
121:	PLNPMMIAAS SICTVFGITA SVVLDPLHVW LYCFISSIFF IFEMVVAFAI FAITIHDFQT 
181:	IGSPMSLKVV ERLKLMRIVF YVSWMAYPIL WSFSSTGACI MSENTSSVLY LLGDALCKNT 
241:	YGILLWATTW GLLNGKWDRD YVKGRNVDGT LMPEYEQDLE KGNTERYEDA RAGETFEVKM 
301:	FGRTLTSVRR SRRRPRRDIV FNGGDRNRLS DSDSERRRRR KKYQRKDSES ENSSDESMGS 
361:	EHEKNRRKGK KKNKENRRSA PPKEDSTSDT LRDAEIKRIM DLMKRNAGSD IPGLDGDGRL 
421:	RDDGGLIPTR NEEHDDSA