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1.A.8.12.2
The silicon (silicic acid) (undissociated form) transporter, Lsi1 (Ma et al., 2007a, b; Mitani et al., 2008). The barley orthologue Lsi1 (also called NIP2-1) is also a silicon (silicic acid) uptake channel (Chiba et al., 2009). Rice Lsi1 also transports arsenite and pentavalent mono and dimethyl arsenite (Li et al., 2009). In addition to silicon (Si), selenite (Se) uptake is mediated by Lsi1 (Zhao et al., 2010).  Physicochemical and transcriptomic responses of Lactobacillus brevis JLD715 to sodium selenite have been reported (Yang et al. 2021). Many of the world's most important food crops such as rice, barley and maize accumulate silicon (Si) to high levels, resulting in better plant growth and crop yields (van den Berg et al. 2021). The first step in Si accumulation is the uptake of silicic acid by the roots, a process mediated by the NIP subfamily of aquaporins, also named metalloid porins. van den Berg et al. 2021 presented the X-ray crystal structure of the archetypal NIP family member from Oryza sativa (OsNIP2;1). The OsNIP2;1 channel is closed in the crystal structure by the cytoplasmic loop D, which is known to regulate channel opening in classical plant aquaporins. The structure reveals a novel, five-residue extracellular selectivity filter with a large diameter. Unbiased molecular dynamics simulations show a rapid opening of the channel to visualise how silicic acid interacts with the selectivity filter prior to transmembrane diffusion. These results may enable detailed structure-function studies of metalloid porins, including the basis of their substrate selectivity (van den Berg et al. 2021).

Accession Number:Q6Z2T3
Protein Name:Silicon transporter Lsi1
Length:298
Molecular Weight:31978.00
Species:Oryza sativa (Rice) [39947]
Number of TMSs:6
Location1 / Topology2 / Orientation3: Cell membrane1 / Multi-pass membrane protein2
Substrate Silicic acid

Cross database links:

RefSeq: NP_001048108.1   
Entrez Gene ID: 4330713   
Pfam: PF00230   
KEGG: osa:4330713   

Gene Ontology

GO:0048226 C:Casparian strip
GO:0016021 C:integral to membrane
GO:0005886 C:plasma membrane
GO:0015115 F:silicate transmembrane transporter activity
GO:0015708 P:silicate transport
GO:0055085 P:transmembrane transport

References (6)

[1] “A silicon transporter in rice.”  Ma J.F.et.al.   16572174
[2] “The map-based sequence of the rice genome.”  International rice genome sequencing project (IRGSP)et.al.   16100779
[3] “Curated genome annotation of Oryza sativa ssp. japonica and comparative genome analysis with Arabidopsis thaliana.”  The rice annotation project (RAP)et.al.   17210932
[4] “The genomes of Oryza sativa: a history of duplications.”  Yu J.et.al.   15685292
[5] “Collection, mapping, and annotation of over 28,000 cDNA clones from japonica rice.”  The rice full-length cDNA consortiumet.al.   12869764
[6] “Identification of 33 rice aquaporin genes and analysis of their expression and function.”  Sakurai J.et.al.   16033806

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FASTA formatted sequence
1:	MASNNSRTNS RANYSNEIHD LSTVQNGTMP TMYYGEKAIA DFFPPHLLKK VVSEVVATFL 
61:	LVFMTCGAAG ISGSDLSRIS QLGQSIAGGL IVTVMIYAVG HISGAHMNPA VTLAFAVFRH 
121:	FPWIQVPFYW AAQFTGAICA SFVLKAVIHP VDVIGTTTPV GPHWHSLVVE VIVTFNMMFV 
181:	TLAVATDTRA VGELAGLAVG SAVCITSIFA GAISGGSMNP ARTLGPALAS NKFDGLWIYF 
241:	LGPVMGTLSG AWTYTFIRFE DTPKEGSSQK LSSFKLRRLR SQQSIAADDV DEMENIQV