Q6XNP7 (HPI_HEVBR) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names

Recommended name:
Protease inhibitor HPI

Alternative name(s):
HbPI1
Protease inhibitor 1

Gene names

Name:

PI1

Organism

Hevea brasiliensis (Para rubber tree) (Siphonia brasiliensis)

Taxonomic identifier

3981 [NCBI]

Taxonomic lineage

Eukaryota › Viridiplantae › Streptophyta › Embryophyta › Tracheophyta › Spermatophyta › Magnoliophyta › eudicotyledons › core eudicotyledons › rosids › fabids › Malpighiales › Euphorbiaceae › Crotonoideae › Micrandreae › Hevea

Protein attributes

Sequence length	70 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is further processed into a mature form.
Protein existence	Evidence at protein level

General annotation (Comments)

Function	Inhibitor of serine proteases, strongly inhibits subtilisin A and weakly inhibits trypsin. Does not inhibit chymotrypsin, papain, pepsin, pronase E, protease type XIII and thermolysin. HPI-1 inhibits subtilisin A with an Ki of 0.21 nM. HPI-2a inhibits subtilisin A with an Ki of 0.08 nM. HPI-2b inhibits subtilisin A with an Ki of 0.1 nM. Ref.2
Subunit structure	Monomer and homodimer; disulfide-linked. Ref.2
Post-translational modification	Occurs in 3 forms that differ in the modification of Cys-5, HPI-1 forms a homodimer through a disulfide bond, HPI-2a is modified by glutathionylation, and HPI-2b is covalently modified by addition of an unidentified adduct but not by a disulfide linkage. Ref.2
Sequence similarities	Belongs to the protease inhibitor I13 (potato type I serine protease inhibitor) family. [View classification]
Mass spectrometry	Molecular mass is 14894 Da from positions 2 - 70. Determined by MALDI. HPI-1 homodimer. Ref.2 Molecular mass is 7758 Da from positions 2 - 70. Determined by MALDI. HPI-2a. Ref.2 Molecular mass is 7566 Da from positions 2 - 70. Determined by MALDI. HPI-2b. Ref.2

Ontologies

Keywords
Molecular function	Protease inhibitor Serine protease inhibitor
PTM	Acetylation Disulfide bond Glutathionylation
Technical term	Direct protein sequencing
Gene Ontology (GO)
Biological process	response to wounding Inferred from electronic annotation. Source: InterPro
Molecular function	serine-type endopeptidase inhibitor activity Inferred from direct assay Ref.2. Source: UniProtKB
Complete GO annotation...

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Initiator methionine	1	1	Removed Ref.2
	Chain	2 – 70	69	Protease inhibitor HPI Ref.2		PRO_0000273520
Sites
	Site	46 – 47	2	Reactive bond By similarity UniProtKB P82381
Amino acid modifications
	Modified residue	2	1	N-acetylalanine Ref.2
	Modified residue	5	1	S-glutathionyl cysteine; alternate
	Disulfide bond	5		Interchain; alternate Ref.2
Experimental info
	Sequence conflict	9 – 10	2	NS → DA in AAP46156. Ref.1

Sequences

	Sequence		Length	Mass (Da)
	Q6XNP7 [UniParc]. Last modified January 23, 2007. Version 2. Checksum: A79F2ADDE8CD2E81	FASTA	70	7,547
	10 20 30 40 50 60 MASQCPVKNS WPELVGTNGD IAAGIIQTEN ANVKAIVVKE GLPITQDLNF NRVRVFVDEN 70 RVVTQVPAIG

References

[1]

"Transcriptome analysis reveals novel features of the molecular events occurring in the laticifers of Hevea brasiliensis (para rubber tree)." Ko J.-H., Chow K.-S., Han K.-H. Plant Mol. Biol. 53:479-492(2003) [PubMed: 15010614] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA]. Tissue: Latex.

[2]

"Isolation and characterization of isoinhibitors of the potato protease inhibitor I family from the latex of the rubber trees, Hevea brasiliensis." Sritanyarat W., Pearce G., Siems W.F., Ryan C.A., Wititsuwannakul R., Wititsuwannakul D. Phytochemistry 67:1644-1650(2006) [PubMed: 16438995] [Abstract] Cited for: PROTEIN SEQUENCE OF 2-70, FUNCTION, MASS SPECTROMETRY, GLUTATHIONE BINDING, DISULFIDE BOND, ACETYLATION AT ALA-2. Tissue: Latex.

Cross-references

Sequence databases
EMBL GenBank DDBJ	AY221985 mRNA. Translation: AAP46156.1.
3D structure databases
HSSP	HSSP built from PDB template 1DWM based on UniProtKB P82381.
ProteinModelPortal	Q6XNP7.
ModBase	Search...
Protein family/group databases
Allergome	8756. Hev b SPI.
Protocols and materials databases
StructuralBiologyKnowledgebase	Search...
Family and domain databases
InterPro	IPR000864. Prot_inh_pot1. [Graphical view]
Gene3D	G3DSA:3.30.10.10. Prot_inh_pot1. 1 hit.
Pfam	PF00280. potato_inhibit. 1 hit. [Graphical view]
PRINTS	PR00292. POTATOINHBTR.
ProDom	PD002604. Prot_inh_pot1. 1 hit. [Graphical view] [Entries sharing at least one domain]
SUPFAM	SSF54654. Prot_inh_pot1. 1 hit.
PROSITE	PS00285. POTATO_INHIBITOR. 1 hit. [Graphical view]
ProtoNet	Search...

Entry information

Entry name

HPI_HEVBR

Accession

Primary (citable) accession number: Q6XNP7

Entry history

Integrated into UniProtKB/Swiss-Prot:	January 23, 2007
Last sequence update:	January 23, 2007
Last modified:	September 21, 2011
This is version 31 of the entry and version 2 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Plant Protein Annotation Program