P69275 (M1_I50A0) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names

Recommended name:
Matrix protein 1
Short name=M1

Gene names

Name:

M

Organism

Influenza A virus (strain A/Fort Warren/1/1950 H1N1)

Taxonomic identifier

384525 [NCBI]

Taxonomic lineage

Viruses › ssRNA viruses › ssRNA negative-strand viruses › Orthomyxoviridae › Influenzavirus A › Influenza A virus › H1N1 subtype

Virus host

Aves [TaxID: 8782]
Homo sapiens (Human) [TaxID: 9606]
Sus scrofa (Pig) [TaxID: 9823]

Protein attributes

Sequence length	252 AA.
Sequence status	Complete.
Protein existence	Inferred from homology

General annotation (Comments)

Function	Plays critical roles in virus replication, from virus entry and uncoating to assembly and budding of the virus particle. M1 binding to ribonucleocapsids (RNPs) in nucleus seems to inhibit viral transcription. Interaction of viral NEP with M1-RNP is thought to promote nuclear export of the complex, which is targeted to the virion assembly site at the apical plasma membrane in polarized epithelial cells. Interactions with NA and HA may bring M1, a non-raft-associated protein, into lipid rafts. Forms a continuous shell on the inner side of the lipid bilayer in virion, where it binds the RNP. During virus entry into cell, the M2 ion channel acidifies the internal virion core, inducing M1 dissociation from the RNP. M1-free RNPs are transported to the nucleus, where viral transcription and replication can take place By similarity. Determines the virion's shape: spherical or filamentous. Clinical isolates of influenza are characterized by the presence of significant proportion of filamentous virions, whereas after multiple passage on eggs or cell culture, virions have only spherical morphology. Filamentous virions are thought to be important to infect neighboring cells, and spherical virions more suited to spread through aerosol between hosts organisms By similarity.
Subunit structure	Homodimer and homomultimer. Interacts with NEP By similarity. Binds ribonucleocapsid by both interacting with genomic RNA and NP protein. May interact with HA and NA By similarity. Cannot bind NP without genomic RNA By similarity.
Subcellular location	Virion membrane; Peripheral membrane protein; Cytoplasmic side By similarity. Host nucleus By similarity.
Miscellaneous	Most abundant protein in virion. When expressed alone can form virus-like particles in transfected cells.
Sequence similarities	Belongs to the influenza viruses Matrix protein M1 family.

Ontologies

Keywords
Biological process	Host-virus interaction Inhibition of host complement factors by virus Viral immunoevasion
Cellular component	Host nucleus Membrane Viral matrix protein Virion
Coding sequence diversity	Alternative splicing
Ligand	RNA-binding
Gene Ontology (GO)
Biological_process	suppression by virus of host complement activation Inferred from electronic annotation. Source: UniProtKB-KW
Cellular_component	host cell nucleus Inferred from electronic annotation. Source: UniProtKB-SubCell virion membrane Inferred from electronic annotation. Source: UniProtKB-SubCell
Molecular_function	RNA binding Inferred from electronic annotation. Source: UniProtKB-KW structural molecule activity Inferred from electronic annotation. Source: InterPro
Complete GO annotation...

Alternative products

This entry describes 2 isoforms produced by alternative splicing. [Align] [Select]

Note: Only the first 9 residues are shared by the 2 isoforms.

Isoform M1 (identifier: P69275-1)

This isoform has been chosen as the 'canonical' sequence. All positional information in this entry refers to it. This is also the sequence that appears in the downloadable versions of the entry.

Isoform M2 (identifier: P10921-1)

The sequence of this isoform can be found in the external entry P10921.
Isoforms of the same protein are often annotated in two different entries if their sequences differ significantly.

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Chain	1 – 252	252	Matrix protein 1		PRO_0000078854
Regions
	Region	1 – 164	164	Membrane-binding By similarity
	Region	165 – 252	88	RNP-binding By similarity
	Motif	101 – 105	5	Nuclear localization signal By similarity

Sequences

	Sequence		Length	Mass (Da)
	Isoform M1 [UniParc]. Last modified March 1, 2005. Version 1. Checksum: 7317397B86DFC877	FASTA	252	27,903
	10 20 30 40 50 60 MSLLTEVETY VLSIVPSGPL KAEIAQRLED VFAGKNTDLE ALMEWLKTRP ILSPLTKGIL 70 80 90 100 110 120 GFVFTLTVPS ERGLQRRRFV QNALNGNGDP NNMDRAVKLY RKLKREITFH GAKEIALSYS 130 140 150 160 170 180 AGALASCMGL IYNRMGAVTT EVAFGLVCAT CEQIADSQHR SHRQMVTTTN PLIRHENRMV 190 200 210 220 230 240 LASTTAKAME QMAGSSEQAA EAMEVASQAR QMVQAMRAIG THPRSSAGLK DDLLENLQAY 250 QKRMGVQMQR FK
	Isoform M2 [UniParc]. See P10921.		–	–

References

[1]	"Nucleotide sequences of influenza A virus RNA segment 7: a comparison of five isolates." Zebedee S.L., Lamb R.A. Nucleic Acids Res. 17:2870-2870(1989) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC RNA].

Cross-references

Sequence databases
EMBL GenBank DDBJ	X08091 Genomic RNA. Translation: CAA30888.1.
PIR	S14616.
3D structure databases
ProteinModelPortal	P69275.
SMR	P69275. Positions 1-158.
ModBase	Search...
Protocols and materials databases
StructuralBiologyKnowledgebase	Search...
Family and domain databases
Gene3D	1.10.10.180. 1 hit. 1.20.91.10. 1 hit.
InterPro	IPR013188. Flu_matrix_M1_C. IPR001561. Flu_matrix_M1_N. IPR015423. Flu_matrix_M1_N_sub1. IPR015799. Flu_matrix_M1_N_sub2. [Graphical view]
Pfam	PF00598. Flu_M1. 1 hit. PF08289. Flu_M1_C. 1 hit. [Graphical view]
ProDom	PD596253. Flu_matrix_M1_C. 1 hit. PD001061. Flu_matrix_M1_N. 1 hit. [Graphical view] [Entries sharing at least one domain]
SMART	SM00759. Flu_M1_C. 1 hit. [Graphical view]
SUPFAM	SSF48145. Flu_M1. 1 hit.
ProtoNet	Search...

Entry information

Entry name

M1_I50A0

Accession

Primary (citable) accession number: P69275
Secondary accession number(s): P10918

Entry history

Integrated into UniProtKB/Swiss-Prot:	March 1, 2005
Last sequence update:	March 1, 2005
Last modified:	April 3, 2013
This is version 53 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Viral Protein Annotation Program