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- FUNCTION: Binds to sialic acid-containing receptors on the cell surface, bringing about the attachment of the virus particle to the cell. Plays a major role in the determination of host range restriction and virulence. Class I viral fusion protein. Responsible for penetration of the virus into the cell cytoplasm by mediating the fusion of the membrane of the endocytosed virus particle with the endosomal membrane. Low pH in endosomes induce an irreversible conformational change in HA2, releasing the fusion hydrophobic peptide. Several trimers are required to form a competent fusion pore (By similarity).
- SUBUNIT: Homotrimer of disulfide-linked HA1-HA2 (By similarity).
- SUBCELLULAR LOCATION: Virion membrane; Single-pass type I membrane protein (Potential). Host apical cell membrane; Single-pass type I membrane protein. Note=Targeted to the apical plasma membrane in epithelial polarized cells through a signal present in the transmembrane domain. Associated with glycosphingolipid- and cholesterol-enriched detergent-resistant lipid rafts (By similarity).
- PTM: In natural infection, inactive HA is matured into HA1 and HA2 outside the cell by one or more trypsin-like, arginine-specific endoprotease secreted by the bronchial epithelial cells. One identified protease that may be involved in this process is secreted in lungs by Clara cells (By similarity).
- PTM: Palmitoylated (By similarity).
- MISCELLANEOUS: Major glycoprotein, comprises over 80% of the envelope proteins present in virus particle.
- MISCELLANEOUS: The extent of infection into host organism is determined by HA. Influenza viruses bud from the apical surface of polarized epithelial cells (e.g. bronchial epithelial cells) into lumen of lungs and are therefore usually pneumotropic. The reason is that HA is cleaved by tryptase clara which is restricted to lungs. However, HAs of H5 and H7 pantropic avian viruses subtypes can be cleaved by furin and subtilisin-type enzymes, allowing the virus to grow in other organs than lungs.
- MISCELLANEOUS: The influenza A genome consist of 8 RNA segments. Genetic variation of hemagglutinin and/or neuraminidase genes results in the emergence of new influenza strains. The mechanism of variation can be the result of point mutations or the result of genetic reassortment between segments of two different strains.
- SIMILARITY: Belongs to the influenza viruses hemagglutinin family.
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Copyrighted by the UniProt Consortium, see http://www.uniprot.org/terms.
Distributed under the Creative Commons Attribution-NoDerivs License.
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| Length: 571 AA [This is the length of the unprocessed precursor] |
Molecular weight: 64105 Da [This is the MW of the unprocessed precursor] |
CRC64: 718DAA0F291CE349 [This is a checksum on the sequence] |
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10 20 30 40 50 60
MLSLIMRTVI ALSYIFCLAF GQGLPWNDNN TATLCLGHHA VPNGTIVKTI TDDQIEVTNA
70 80 90 100 110 120
TELVQSSSTG KICNNPHRIL DGGNCTLIDA LLGDPHCNVF QYETWDLFVE RTNAFSNCYP
130 140 150 160 170 180
YDVPDYASLR SIVASSGTLE FFAESFTWTG VTQNGGSSAC KRGTASSFFS RLNWLTKSGN
190 200 210 220 230 240
AYPLLNVTMP NNDNFDKLYI WGVHHPSTNQ EQTELYVQAS GRVTVSTRKS QQTVIPNIGS
250 260 270 280 290 300
RPWVRGQSGR VSIYWTIVKP GDVLVINSNG NLIAPRGYFK VRTGKSSIMR SDAPIDTCIS
310 320 330 340 350 360
ECITPNGSIP NDKPFQNVNK ITYGACPKYV KQNTLKLATG MRNVPEKQIR GIFGAIAGFI
370 380 390 400 410 420
ENGWEGMIDG WYGFRHQNSE GTGQAADLKS TQAALDQING KLNRVIEKTN EKFHQIEKEF
430 440 450 460 470 480
SEVEGRIQDL EKYVEDTKID LWSYNAELLV ALENQHTIDL TDSEMNKLFE KTRRQLRENA
490 500 510 520 530 540
EDMGNGCFKI YHNCDNACIE SIRNGTYDHN IYRDEALNNR FQIKGVELKS GYKDWILWIS
550 560 570
FAISCFLLCV VLLGFIMWAC QKGNIRCNIC F
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Q03909 in FASTA format |
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