ID Q2NGL3_METST Unreviewed; 253 AA. AC Q2NGL3; DT 07-FEB-2006, integrated into UniProtKB/TrEMBL. DT 07-FEB-2006, sequence version 1. DT 02-SEP-2026, entry version 92. DE RecName: Full=Probable S-methyl-5'-thioinosine phosphorylase {ECO:0000256|HAMAP-Rule:MF_01963}; DE EC=2.4.2.44 {ECO:0000256|HAMAP-Rule:MF_01963}; DE AltName: Full=5'-methylthioinosine phosphorylase {ECO:0000256|HAMAP-Rule:MF_01963}; DE Short=MTI phosphorylase {ECO:0000256|HAMAP-Rule:MF_01963}; DE Short=MTIP {ECO:0000256|HAMAP-Rule:MF_01963}; GN OrderedLocusNames=Msp_0642 {ECO:0000313|EMBL:ABC57040.1}; OS Methanosphaera stadtmanae (strain ATCC 43021 / DSM 3091 / JCM 11832 / OS MCB-3). OC Archaea; Methanobacteriati; Methanobacteriota; Methanomada group; OC Methanobacteria; Methanobacteriales; Methanobacteriaceae; Methanosphaera. OX NCBI_TaxID=339860 {ECO:0000313|EMBL:ABC57040.1, ECO:0000313|Proteomes:UP000001931}; RN [1] {ECO:0000313|EMBL:ABC57040.1, ECO:0000313|Proteomes:UP000001931} RP NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. RC STRAIN=ATCC 43021 / DSM 3091 / JCM 11832 / MCB-3 RC {ECO:0000313|Proteomes:UP000001931}; RX PubMed=16385054; DOI=10.1128/JB.188.2.642-658.2006; RA Fricke W.F., Seedorf H., Henne A., Kruer M., Liesegang H., Hedderich R., RA Gottschalk G., Thauer R.K.; RT "The genome sequence of Methanosphaera stadtmanae reveals why this human RT intestinal archaeon is restricted to methanol and H2 for methane formation RT and ATP synthesis."; RL J. Bacteriol. 188:642-658(2006). CC -!- FUNCTION: Catalyzes the phosphorolytic cleavage of S-methyl-5'- CC thioinosine (MTI) to hypoxanthine and 5-methylthioribose-1-phosphate. CC Involved in the breakdown of S-methyl-5'-thioadenosine (MTA), a major CC by-product of polyamine biosynthesis. Catabolism of (MTA) occurs via CC deamination to MTI and phosphorolysis to hypoxanthine. CC {ECO:0000256|HAMAP-Rule:MF_01963}. CC -!- CATALYTIC ACTIVITY: CC Reaction=S-methyl-5'-thioinosine + phosphate = 5-(methylsulfanyl)- CC alpha-D-ribose 1-phosphate + hypoxanthine; Xref=Rhea:RHEA:30643, CC ChEBI:CHEBI:17368, ChEBI:CHEBI:43474, ChEBI:CHEBI:48595, CC ChEBI:CHEBI:58533; EC=2.4.2.44; Evidence={ECO:0000256|HAMAP- CC Rule:MF_01963}; CC -!- PATHWAY: Purine metabolism; purine nucleoside salvage. CC {ECO:0000256|HAMAP-Rule:MF_01963}. CC -!- SUBUNIT: Homotrimer. {ECO:0000256|HAMAP-Rule:MF_01963}. CC -!- MISCELLANEOUS: Although this enzyme belongs to the family of MTA CC phosphorylases based on sequence homology, it has been shown that CC conserved amino acid substitutions in the substrate binding pocket CC convert the substrate specificity of this enzyme from 6-aminopurines to CC 6-oxopurines. {ECO:0000256|HAMAP-Rule:MF_01963}. CC -!- SIMILARITY: Belongs to the PNP/MTAP phosphorylase family. MTAP CC subfamily. {ECO:0000256|HAMAP-Rule:MF_01963}. CC -!- CAUTION: Lacks conserved residue(s) required for the propagation of CC feature annotation. {ECO:0000256|HAMAP-Rule:MF_01963}. CC --------------------------------------------------------------------------- CC Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms CC Distributed under the Creative Commons Attribution (CC BY 4.0) License CC --------------------------------------------------------------------------- DR EMBL; CP000102; ABC57040.1; -; Genomic_DNA. DR RefSeq; WP_011406240.1; NC_007681.1. DR AlphaFoldDB; Q2NGL3; -. DR STRING; 339860.Msp_0642; -. DR GeneID; 3856251; -. DR KEGG; mst:Msp_0642; -. DR eggNOG; arCOG01327; Archaea. DR HOGENOM; CLU_054456_0_2_2; -. DR OrthoDB; 7681at2157; -. DR UniPathway; UPA00606; -. DR Proteomes; UP000001931; Chromosome. DR GO; GO:0005829; C:cytosol; IEA:TreeGrafter. DR GO; GO:0017061; F:S-methyl-5-thioadenosine phosphorylase activity; IEA:InterPro. DR GO; GO:0006166; P:purine ribonucleoside salvage; IEA:UniProtKB-UniRule. DR CDD; cd09010; MTAP_SsMTAPII_like_MTIP; 1. DR Gene3D; 3.40.50.1580; Nucleoside phosphorylase domain; 1. DR HAMAP; MF_01963; MTAP; 1. DR InterPro; IPR010044; MTAP. DR InterPro; IPR000845; Nucleoside_phosphorylase_d. DR InterPro; IPR035994; Nucleoside_phosphorylase_sf. DR NCBIfam; NF006599; PRK09136.1; 1. DR PANTHER; PTHR42679; S-METHYL-5'-THIOADENOSINE PHOSPHORYLASE; 1. DR PANTHER; PTHR42679:SF2; S-METHYL-5'-THIOADENOSINE PHOSPHORYLASE; 1. DR Pfam; PF01048; PNP_UDP_1; 1. DR SUPFAM; SSF53167; Purine and uridine phosphorylases; 1. PE 3: Inferred from homology; KW Glycosyltransferase {ECO:0000256|ARBA:ARBA00022676, ECO:0000256|HAMAP- KW Rule:MF_01963}; Purine salvage {ECO:0000256|HAMAP-Rule:MF_01963}; KW Reference proteome {ECO:0000313|Proteomes:UP000001931}; KW Transferase {ECO:0000256|ARBA:ARBA00022679, ECO:0000256|HAMAP- KW Rule:MF_01963}. FT DOMAIN 2..233 FT /note="Nucleoside phosphorylase" FT /evidence="ECO:0000259|Pfam:PF01048" FT BINDING 8 FT /ligand="phosphate" FT /ligand_id="ChEBI:CHEBI:43474" FT /evidence="ECO:0000256|HAMAP-Rule:MF_01963" FT BINDING 50..51 FT /ligand="phosphate" FT /ligand_id="ChEBI:CHEBI:43474" FT /evidence="ECO:0000256|HAMAP-Rule:MF_01963" FT BINDING 175 FT /ligand="substrate" FT /evidence="ECO:0000256|HAMAP-Rule:MF_01963" FT BINDING 176 FT /ligand="phosphate" FT /ligand_id="ChEBI:CHEBI:43474" FT /evidence="ECO:0000256|HAMAP-Rule:MF_01963" FT BINDING 199..201 FT /ligand="substrate" FT /evidence="ECO:0000256|HAMAP-Rule:MF_01963" FT SITE 157 FT /note="Important for substrate specificity" FT /evidence="ECO:0000256|HAMAP-Rule:MF_01963" FT SITE 211 FT /note="Important for substrate specificity" FT /evidence="ECO:0000256|HAMAP-Rule:MF_01963" SQ SEQUENCE 253 AA; 27809 MW; EB7C8D5A97DBE5DA CRC64; MIGIIGGTGT KALLETYSIV DKKDVKTEYG QAPQITILDI NNKEVAYIPR HSQGHSVPPH KINYRANIEA LKTIGVNQVY ATNSVGSLDT NIEPGSILIP DNFIDFTHNR VSTFFDNEVV HIDCTNPYCE TLRTNLITGN DVHPYGIYIA TEGPRFETGA EIQFYKLIGG KVVGMTGVPE VVLAKEKQMC YSSICAVTNY AAAISPNKLT ITEVIDAMKD CEEKLIKLIT KTIKNTVVSR DCGCQHILDD AII //