P02920 (LACY_ECOLI) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names

Recommended name:
Lactose permease

Alternative name(s):
Lactose-proton symport

Gene names

Name:	lacY
Ordered Locus Names:	b0343, JW0334

Organism

Escherichia coli (strain K12) [Reference proteome] [HAMAP]

Taxonomic identifier

83333 [NCBI]

Taxonomic lineage

cellular organisms › Bacteria › Proteobacteria › Gammaproteobacteria › Enterobacteriales › Enterobacteriaceae › Escherichia › Escherichia coli

Protein attributes

Sequence length	417 AA.
Sequence status	Complete.
Protein existence	Evidence at protein level

General annotation (Comments)

Function	Responsible for transport of beta-galactosides into the cell, with the concomitant import of a proton (symport system).
Subunit structure	Monomer.
Subcellular location	Cell inner membrane; Multi-pass membrane protein.
Sequence similarities	Belongs to the LacY/RafB permease family.
Mass spectrometry	Molecular mass is 47357 Da from positions 1 - 417. Determined by ESI. Ref.12

Ontologies

Keywords
Biological process	Sugar transport Symport Transport
Cellular component	Cell inner membrane Cell membrane Membrane
Domain	Transmembrane Transmembrane helix
PTM	Formylation
Technical term	3D-structure Complete proteome Reference proteome
Gene Ontology (GO)
Cellular_component	integral to plasma membrane Inferred from direct assay PubMed 7028742. Source: EcoCyc
Molecular_function	lactose binding Inferred from direct assay Ref.14. Source: EcoliWiki lactose:hydrogen symporter activity Inferred from direct assay PubMed 3520229PubMed 7028742. Source: EcoCyc
Complete GO annotation...

Sequence annotation (Features)

Feature key

Position(s)

Length

Description

Graphical view

Feature identifier

Molecule processing

Chain

1 – 417

417

Lactose permease

PRO_0000196184

Regions

Topological domain

1 – 7

7

Cytoplasmic Ref.6 Ref.7 Ref.8 Ref.13

Transmembrane

8 – 34

27

Helical; Name=1

Topological domain

35 – 41

7

Periplasmic Ref.6 Ref.7 Ref.8 Ref.13

Transmembrane

42 – 70

29

Helical; Name=2

Topological domain

71 – 74

4

Cytoplasmic Ref.6 Ref.7 Ref.8 Ref.13

Transmembrane

75 – 100

26

Helical; Name=3

Topological domain

101 – 104

4

Periplasmic Ref.6 Ref.7 Ref.8 Ref.13

Transmembrane

105 – 129

25

Helical; Name=4

Topological domain

130 – 140

11

Cytoplasmic Ref.6 Ref.7 Ref.8 Ref.13

Transmembrane

141 – 163

23

Helical; Name=5

Topological domain

164 – 166

3

Periplasmic Ref.6 Ref.7 Ref.8 Ref.13

Transmembrane

167 – 186

20

Helical; Name=6

Topological domain

187 – 220

34

Cytoplasmic Ref.6 Ref.7 Ref.8 Ref.13

Transmembrane

221 – 249

29

Helical; Name=7

Topological domain

250 – 253

4

Periplasmic Ref.6 Ref.7 Ref.8 Ref.13

Transmembrane

254 – 278

25

Helical; Name=8

Topological domain

279 – 288

10

Cytoplasmic Ref.6 Ref.7 Ref.8 Ref.13

Transmembrane

289 – 308

20

Helical; Name=9

Topological domain

309 – 311

3

Periplasmic Ref.6 Ref.7 Ref.8 Ref.13

Transmembrane

312 – 334

23

Helical; Name=10

Topological domain

335 – 346

12

Cytoplasmic Ref.6 Ref.7 Ref.8 Ref.13

Transmembrane

347 – 374

28

Helical; Name=11

Topological domain

375 – 377

3

Periplasmic Ref.6 Ref.7 Ref.8 Ref.13

Transmembrane

378 – 398

21

Helical; Name=12

Topological domain

399 – 417

19

Cytoplasmic Ref.6 Ref.7 Ref.8 Ref.13

Sites

Site

126

1

Substrate binding

Site

144

1

Substrate binding

Site

269

1

Substrate binding and proton translocation

Site

302

1

Proton translocation

Site

322

1

Proton translocation

Site

325

1

Proton translocation

Amino acid modifications

Modified residue

1

1

N-formylmethionine; partial

Experimental info

Mutagenesis

237

1

D → N or G: Defect in melibiose transport.

Mutagenesis

358

1

K → T: Defect in melibiose transport.

Secondary structure

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417

Helix Strand Turn

Details...

Turn

2 – 4

3

Helix

7 – 26

20

Turn

27 – 29

3

Helix

30 – 35

6

Turn

36 – 38

3

Turn

42 – 44

3

Helix

46 – 67

22

Helix

68 – 70

3

Helix

71 – 73

3

Helix

75 – 82

8

Helix

87 – 93

7

Helix

95 – 100

6

Helix

105 – 108

4

Helix

109 – 111

3

Helix

116 – 119

4

Helix

122 – 136

15

Helix

140 – 143

4

Beta strand

144 – 146

3

Turn

147 – 149

3

Helix

150 – 164

15

Helix

167 – 170

4

Turn

171 – 179

9

Helix

180 – 183

4

Beta strand

193 – 195

3

Beta strand

197 – 203

7

Helix

210 – 216

7

Helix

220 – 249

30

Beta strand

251 – 253

3

Helix

254 – 257

4

Helix

259 – 286

28

Helix

288 – 306

19

Helix

312 – 318

7

Helix

321 – 340

20

Helix

343 – 354

12

Turn

355 – 357

3

Helix

358 – 365

8

Helix

367 – 370

4

Helix

372 – 375

4

Helix

377 – 396

20

Beta strand

408 – 413

6

Turn

414 – 416

3

Sequences

	Sequence		Length	Mass (Da)
	P02920 [UniParc]. Last modified July 21, 1986. Version 1. Checksum: 24A8062F628CDA32	FASTA	417	46,503
	10 20 30 40 50 60 MYYLKNTNFW MFGLFFFFYF FIMGAYFPFF PIWLHDINHI SKSDTGIIFA AISLFSLLFQ 70 80 90 100 110 120 PLFGLLSDKL GLRKYLLWII TGMLVMFAPF FIFIFGPLLQ YNILVGSIVG GIYLGFCFNA 130 140 150 160 170 180 GAPAVEAFIE KVSRRSNFEF GRARMFGCVG WALCASIVGI MFTINNQFVF WLGSGCALIL 190 200 210 220 230 240 AVLLFFAKTD APSSATVANA VGANHSAFSL KLALELFRQP KLWFLSLYVI GVSCTYDVFD 250 260 270 280 290 300 QQFANFFTSF FATGEQGTRV FGYVTTMGEL LNASIMFFAP LIINRIGGKN ALLLAGTIMS 310 320 330 340 350 360 VRIIGSSFAT SALEVVILKT LHMFEVPFLL VGCFKYITSQ FEVRFSATIY LVCFCFFKQL 370 380 390 400 410 AMIFMSVLAG NMYESIGFQG AYLVLGLVAL GFTLISVFTL SGPGPLSLLR RQVNEVA

References

	« Hide 'large scale' referencesShow 'large scale' references »
[1]	"Sequence of the lactose permease gene." Buechel D.E., Gronenborn B., Mueller-Hill B. Nature 283:541-545(1980) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA].
[2]	Pastore J.C., Larigan J.D., Consler T.G., Kaback H.R. Submitted (SEP-1990) to the EMBL/GenBank/DDBJ databases Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA]. Strain: K12.
[3]	"Sequence of minutes 4-25 of Escherichia coli." Chung E., Allen E., Araujo R., Aparicio A.M., Davis K., Duncan M., Federspiel N., Hyman R., Kalman S., Komp C., Kurdi O., Lew H., Lin D., Namath A., Oefner P., Roberts D., Schramm S., Davis R.W. Submitted (JAN-1997) to the EMBL/GenBank/DDBJ databases Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: K12 / MG1655 / ATCC 47076.
[4]	"The complete genome sequence of Escherichia coli K-12." Blattner F.R., Plunkett G. III, Bloch C.A., Perna N.T., Burland V., Riley M., Collado-Vides J., Glasner J.D., Rode C.K., Mayhew G.F., Gregor J., Davis N.W., Kirkpatrick H.A., Goeden M.A., Rose D.J., Mau B., Shao Y. Science 277:1453-1474(1997) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: K12 / MG1655 / ATCC 47076.
[5]	"Highly accurate genome sequences of Escherichia coli K-12 strains MG1655 and W3110." Hayashi K., Morooka N., Yamamoto Y., Fujita K., Isono K., Choi S., Ohtsubo E., Baba T., Wanner B.L., Mori H., Horiuchi T. Mol. Syst. Biol. 2:E1-E5(2006) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: K12 / W3110 / ATCC 27325 / DSM 5911.
[6]	"The distribution of positively charged residues in bacterial inner membrane proteins correlates with the trans-membrane topology." von Heijne G. EMBO J. 5:3021-3027(1986) [PubMed] [Europe PMC] [Abstract] Cited for: TOPOLOGY.
[7]	"lac permease of Escherichia coli: topology and sequence elements promoting membrane insertion." Calamia J., Manoil C. Proc. Natl. Acad. Sci. U.S.A. 87:4937-4941(1990) [PubMed] [Europe PMC] [Abstract] Cited for: TOPOLOGY.
[8]	"Membrane topology of helices VII and XI in the lactose permease of Escherichia coli studied by lacY-phoA fusion analysis and site-directed spectroscopy." Ujwal M.L., Jung H., Bibi E., Manoil C., Altenbach C., Hubbell W.L., Kaback H.R. Biochemistry 34:14909-14917(1995) [PubMed] [Europe PMC] [Abstract] Cited for: TOPOLOGY.
[9]	"The interaction between aspartic acid 237 and lysine 358 in the lactose carrier of Escherichia coli." King S.C., Hansen C.L., Wilson T.H. Biochim. Biophys. Acta 1062:177-186(1991) [PubMed] [Europe PMC] [Abstract] Cited for: MUTAGENESIS.
[10]	"Amino acid substitution in the lactose carrier protein with the use of amber suppressors." Huang A.-M., Lee J.-I., King S.C., Wilson T.H. J. Bacteriol. 174:5436-5441(1992) [PubMed] [Europe PMC] [Abstract] Cited for: MUTAGENESIS.
[11]	"The lac permease of Escherichia coli: a prototypic energy-transducing membrane protein." Kaback H.R. Biochim. Biophys. Acta 1018:160-162(1990) [PubMed] [Europe PMC] [Abstract] Cited for: REVIEW.
[12]	"Toward the bilayer proteome, electrospray ionization-mass spectrometry of large, intact transmembrane proteins." Whitelegge J.P., le Coutre J., Lee J.C., Engel C.K., Prive G.G., Faull K.F., Kaback H.R. Proc. Natl. Acad. Sci. U.S.A. 96:10695-10698(1999) [PubMed] [Europe PMC] [Abstract] Cited for: MASS SPECTROMETRY OF FORMYLATED FORM.
[13]	"Global topology analysis of the Escherichia coli inner membrane proteome." Daley D.O., Rapp M., Granseth E., Melen K., Drew D., von Heijne G. Science 308:1321-1323(2005) [PubMed] [Europe PMC] [Abstract] Cited for: TOPOLOGY [LARGE SCALE ANALYSIS]. Strain: K12 / MG1655 / ATCC 47076.
[14]	"Structure and mechanism of the lactose permease of Escherichia coli." Abramson J., Smirnova I., Kasho V., Verner G., Kaback H.R., Iwata S. Science 301:610-615(2003) [PubMed] [Europe PMC] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (3.5 ANGSTROMS) OF MUTANT GLY-154.
+	Additional computationally mapped references.

Cross-references

Sequence databases

EMBL
GenBank
DDBJ

J01636 Genomic DNA. Translation: AAA24054.1.
V00295 Genomic DNA. Translation: CAA23571.1.
X56095 Genomic DNA. Translation: CAA39575.1.
U73857 Genomic DNA. Translation: AAB18067.1.
U00096 Genomic DNA. Translation: AAC73446.1.
AP009048 Genomic DNA. Translation: BAE76125.1.

PIR

GREC. A03418.

RefSeq

NP_414877.1. NC_000913.2.
YP_488637.1. NC_007779.1.

3D structure databases

PDBe
RCSB PDB
PDBj

Entry	Method	Resolution (Å)	Chain	Positions	PDBsum
1M2U	model	-	A	1-417	[»]
1PV6	X-ray	3.50	A/B	1-417	[»]
1PV7	X-ray	3.60	A/B	1-417	[»]
2CFP	X-ray	3.30	A	1-417	[»]
2CFQ	X-ray	2.95	A	1-417	[»]
2V8N	X-ray	3.60	A/B	1-417	[»]
2Y5Y	X-ray	3.38	A/B	1-417	[»]

ProteinModelPortal

P02920.

SMR

P02920. Positions 1-417.

ModBase

Search...

Protein-protein interaction databases

DIP

DIP-10080N.

STRING

511145.b0343.

Protein family/group databases

TCDB

2.A.1.5.1. major facilitator superfamily (MFS).

Proteomic databases

PRIDE

P02920.

Protocols and materials databases

StructuralBiologyKnowledgebase

Search...

Genome annotation databases

EnsemblBacteria

AAC73446; AAC73446; b0343.
BAE76125; BAE76125; BAE76125.

GeneID

12934191.
949083.

KEGG

ecj:Y75_p0332.
eco:b0343.

PATRIC

32115819. VBIEscCol129921_0351.

Organism-specific databases

EchoBASE

EB0521.

EcoGene

EG10526. lacY.

Phylogenomic databases

eggNOG

COG0477.

HOGENOM

HOG000114363.

KO

K02532.

OMA

PFLIVGC.

ProtClustDB

PRK09528.

Enzyme and pathway databases

BioCyc

EcoCyc:LACY-MONOMER.
ECOL316407:JW0334-MONOMER.

Gene expression databases

Genevestigator

P02920.

Family and domain databases

InterPro

IPR000576. LacY/RafB_perm_fam.
IPR018457. LacY/RafB_perm_fam_CS.
IPR020846. MFS_dom.
IPR016196. MFS_dom_general_subst_transpt.
[Graphical view]

PANTHER

PTHR24003:SF271. PTHR24003:SF271. 1 hit.

Pfam

PF01306. LacY_symp. 1 hit.
[Graphical view]

PRINTS

PR00174. LACYSMPORT.

SUPFAM

SSF103473. MFS_gen_substrate_transporter. 1 hit.

TIGRFAMs

TIGR00882. 2A0105. 1 hit.

PROSITE

PS00896. LACY_1. 1 hit.
PS00897. LACY_2. 1 hit.
PS50850. MFS. 1 hit.
[Graphical view]

ProtoNet

Search...

Other

EvolutionaryTrace

P02920.

Entry information

Entry name

LACY_ECOLI

Accession

Primary (citable) accession number: P02920
Secondary accession number(s): Q2MC81

Entry history

Integrated into UniProtKB/Swiss-Prot:	July 21, 1986
Last sequence update:	July 21, 1986
Last modified:	May 1, 2013
This is version 131 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Prokaryotic Protein Annotation Program