P84781 (ITR3_SPIOL) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names	Recommended name: Trypsin inhibitor 3 Alternative name(s): SOTI III Trypsin inhibitor III
Organism	Spinacia oleracea (Spinach)
Taxonomic identifier	3562 [NCBI]
Taxonomic lineage	cellular organisms › Eukaryota › Viridiplantae › Streptophyta › Streptophytina › Embryophyta › Tracheophyta › Euphyllophyta › Spermatophyta › Magnoliophyta › eudicotyledons › core eudicotyledons › Caryophyllales › Amaranthaceae › Spinacia

Protein attributes

Sequence length	37 AA.
Sequence status	Complete.
Protein existence	Evidence at protein level

General annotation (Comments)

Function	Trypsin inhibitor. Ref.1
Domain	The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin By similarity.
Sequence similarities	Belongs to the Mirabilis serine proteinase inhibitor family. Ref.1
Mass spectrometry	Molecular mass is 3838.4 Da from positions 1 - 37. Determined by ESI. Ref.1

Ontologies

Keywords
Domain	Knottin
Molecular function	Protease inhibitor Serine protease inhibitor
PTM	Disulfide bond
Technical term	3D-structure Direct protein sequencing
Gene Ontology (GO)
Molecular_function	serine-type endopeptidase inhibitor activity Inferred from electronic annotation. Source: UniProtKB-KW
Complete GO annotation...

Sequence annotation (Features)

Feature key

Position(s)

Length

Description

Graphical view

Feature identifier

Molecule processing

Peptide

1 – 37

37

Trypsin inhibitor 3 Ref.1

PRO_0000292939

Sites

Site

32 – 33

2

Reactive bond for trypsin By similarity UniProtKB P84779

Amino acid modifications

Disulfide bond

4 ↔ 21

By similarity UniProtKB P84779

Disulfide bond

11 ↔ 25

By similarity UniProtKB P84779

Disulfide bond

20 ↔ 36

By similarity UniProtKB P84779

Secondary structure

1

.

.

.

.

.

.

.

.

.

37

Helix Strand Turn

Details...

Beta strand

9 – 11

3

Helix

17 – 19

3

Beta strand

25 – 27

3

Beta strand

29 – 36

8

Sequences

	Sequence		Length	Mass (Da)
	P84781 [UniParc]. Last modified June 26, 2007. Version 1. Checksum: D1F1F78D4EF22274	FASTA	37	3,837
	10 20 30 EDKCSPSGAI CSGFGPPEQC CSGACVPHPI LRIFVCQ

References

[1]

"Trypsin inhibitors from the garden four o'clock (Mirabilis jalapa) and spinach (Spinacia oleracea) seeds: isolation, characterization and chemical synthesis." Kowalska J., Pszczola K., Wilimowska-Pelc A., Lorenc-Kubis I., Zuziak E., Lugowski M., Legowska A., Kwiatkowska A., Sleszynska M., Lesner A., Walewska A., Zablotna E., Rolka K., Wilusz T. Phytochemistry 68:1487-1496(2007) [PubMed] [Europe PMC] [Abstract] Cited for: PROTEIN SEQUENCE, FUNCTION, MASS SPECTROMETRY. Tissue: Seed.

Cross-references

3D structure databases

PDBe
RCSB PDB
PDBj

Entry	Method	Resolution (Å)	Chain	Positions	PDBsum
4AOQ	X-ray	2.00	D/E/F	1-37	[»]
4AOR	X-ray	1.70	D/E/F	1-37	[»]

ModBase

Search...

Protein family/group databases

MEROPS

I90.001.

Protocols and materials databases

StructuralBiologyKnowledgebase

Search...

Family and domain databases

ProtoNet

Search...

Entry information

Entry name

ITR3_SPIOL

Accession

Primary (citable) accession number: P84781

Entry history

Integrated into UniProtKB/Swiss-Prot:	June 26, 2007
Last sequence update:	June 26, 2007
Last modified:	April 3, 2013
This is version 11 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Plant Protein Annotation Program