P05777 (M1_I33A0) 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/Wilson-Smith/1933 H1N1) (Influenza A virus (strain A/WS/1933 H1N1)) [Complete proteome]

Taxonomic identifier

381518 [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	Evidence at protein level

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. Ref.7 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. Ref.7
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. Ref.5
Subcellular location	Virion membrane; Peripheral membrane protein; Cytoplasmic side. Host nucleus.
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
Technical term	Complete proteome
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: P05777-1)

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: P05780-1)

The sequence of this isoform can be found in the external entry P05780.
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_0000078868
Regions
	Region	1 – 164	164	Membrane-binding
	Region	165 – 252	88	RNP-binding
	Motif	101 – 105	5	Nuclear localization signal
Experimental info
	Mutagenesis	41	1	V → A: Induces short filamentous virions. Ref.9
	Mutagenesis	95	1	K → A or R: No effect. Ref.8 Ref.9
	Mutagenesis	97	1	V → A: No effect. Ref.8
	Mutagenesis	98	1	K → A or R: No effect. Ref.8
	Mutagenesis	99	1	L → A: No effect. Ref.8
	Mutagenesis	100 – 103	4	YRKL → AAAA or PPPY: Can't be rescued by reverse genetic. Ref.8
	Mutagenesis	100 – 103	4	YRKL → PTAP: No effect. Ref.8
	Mutagenesis	100	1	Y → A, F or S: No effect. Ref.8
	Mutagenesis	101 – 105	5	RKLKR → SNLNS: 50% loss of RNA binding activity. Ref.4 Ref.8
	Mutagenesis	101 – 102	2	RK → PD: No effect. Ref.8
	Mutagenesis	101	1	R → A: Reduced growth and small-plaque morphology. Virions have an elongated filamentous morphology. Ref.8
	Mutagenesis	101	1	R → K: No effect. Ref.8
	Mutagenesis	102	1	K → A or R: No effect. Ref.8
	Mutagenesis	103	1	L → A, I or V: No effect. Ref.8
	Mutagenesis	104	1	K → A: Can't be rescued by reverse genetic. Ref.8
	Mutagenesis	104	1	K → R: No effect. Ref.8
	Mutagenesis	105	1	R → A: Can't be rescued by reverse genetic. Ref.8
	Mutagenesis	105	1	R → K: Reduced growth and small-plaque morphology. Ref.8
	Mutagenesis	106	1	E → A: Can't be rescued by reverse genetic. Ref.8
	Mutagenesis	148	1	C → A: No effect. Ref.4 Ref.6
	Mutagenesis	148	1	C → S: 31% loss of RNA binding activity. Ref.4 Ref.6
	Mutagenesis	151	1	C → A: No effect. Ref.6
	Mutagenesis	155	1	A → G: Complete loss of virus ability to be rescued in a reverse genetic system. Ref.6
	Mutagenesis	159	1	H → A: No effect. Ref.6
	Mutagenesis	162	1	H → A: No effect. Ref.6
	Mutagenesis	218	1	T → A: No effect on virion morphology. Ref.9
	Sequence conflict	117	1	L → F in AAA43352. Ref.3
	Sequence conflict	219	1	I → V in AAA43352. Ref.3
	Sequence conflict	231	1	D → S in AAA43252. Ref.2

Sequences

	Sequence		Length	Mass (Da)
	Isoform M1 [UniParc]. Last modified July 1, 1989. Version 2. Checksum: 5F300F18D75BBAD3	FASTA	252	27,864
	10 20 30 40 50 60 MSLLTEVETY VLSIVPSGPL KAEIAQRLED VFAGKNTDLE VLMEWLKTRP ILSPLTKGIL 70 80 90 100 110 120 GFVFTLTVPS ERGLQRRRFV QNALNGNGDP NNMDKAVKLY RKLKREITFH GAKEIALSYS 130 140 150 160 170 180 AGALASCMGL IYNRMGAVTT EVAFGLVCAT CEQIADSQHR SHRQMVTTTN PLIRHENRMV 190 200 210 220 230 240 LASTTAKAME QMAGSSEQAA EAMDIASQAR QMVQAMRTIG THPSSSAGLK DDLLENLQAY 250 QKRMGVQMQR FK
	Isoform M2 [UniParc]. See P05780.		–	–

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].
[2]	"Nucleotide sequence of RNA segment 7 and the predicted amino sequence of M1 and M2 proteins of FPV/Weybridge (H7N7) and WSN (H1N1) influenza viruses." Markushin S., Ghiasi H., Sokolov N., Shilov A., Sinitsin B., Brown D., Klimov A., Nayak D. Virus Res. 10:263-272(1988) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC RNA].
[3]	"Transient expression and sequence of the matrix (M1) gene of WSN influenza A virus in a vaccinia vector." Baylor N.W., Zhiping Y.L., Wagner R.R. Virology 163:618-621(1988) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC RNA].
[4]	"Association of influenza virus matrix protein with ribonucleoproteins." Ye Z., Liu T., Offringa D.P., McInnis J., Levandowski R.A. J. Virol. 73:7467-7473(1999) [PubMed] [Europe PMC] [Abstract] Cited for: MUTAGENESIS OF 101-ARG--ARG-105 AND CYS-148.
[5]	"Influenza virus assembly: effect of influenza virus glycoproteins on the membrane association of M1 protein." Ali A., Avalos R.T., Ponimaskin E., Nayak D.P. J. Virol. 74:8709-8719(2000) [PubMed] [Europe PMC] [Abstract] Cited for: INTERACTION WITH HA AND NA.
[6]	"Conserved cysteine and histidine residues in the putative zinc finger motif of the influenza A virus M1 protein are not critical for influenza virus replication." Hui E.K., Ralston K., Judd A.K., Nayak D.P. J. Gen. Virol. 84:3105-3113(2003) [PubMed] [Europe PMC] [Abstract] Cited for: MUTAGENESIS OF CYS-148; CYS-151; ALA-155; HIS-159 AND HIS-162.
[7]	"Reverse genetics studies on the filamentous morphology of influenza A virus." Bourmakina S.V., Garcia-Sastre A. J. Gen. Virol. 84:517-527(2003) [PubMed] [Europe PMC] [Abstract] Cited for: FUNCTION.
[8]	"Basic residues of the helix six domain of influenza virus M1 involved in nuclear translocation of M1 can be replaced by PTAP and YPDL late assembly domain motifs." Hui E.K., Barman S., Yang T.Y., Nayak D.P. J. Virol. 77:7078-7092(2003) [PubMed] [Europe PMC] [Abstract] Cited for: MUTAGENESIS OF LYS-95; VAL-97; LYS-98; LEU-99; TYR-100; ARG-101; LYS-102; LEU-103; LYS-104; ARG-105 AND GLU-106.
[9]	"The M1 matrix protein controls the filamentous phenotype of influenza A virus." Elleman C.J., Barclay W.S. Virology 321:144-153(2004) [PubMed] [Europe PMC] [Abstract] Cited for: MUTAGENESIS OF VAL-41; LYS-95 AND THR-218.

Cross-references

Sequence databases
EMBL GenBank DDBJ	X08088 Genomic RNA. Translation: CAA30882.1. M23920 Genomic RNA. Translation: AAA43252.1. Sequence problems. M19374 Genomic RNA. Translation: AAA43352.1. L25818 Genomic RNA. Translation: AAA91325.1.
PIR	MFIVWS. A28608. S07429.
3D structure databases
ProteinModelPortal	P05777.
SMR	P05777. 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_I33A0

Accession

Primary (citable) accession number: P05777

Entry history

Integrated into UniProtKB/Swiss-Prot:	November 1, 1988
Last sequence update:	July 1, 1989
Last modified:	April 3, 2013
This is version 87 of the entry and version 2 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Viral Protein Annotation Program