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Protein

Hapless 2

Gene

HAP2

Organism
Chlamydomonas reinhardtii (Chlamydomonas smithii)
Status
Reviewed-Annotation score: Annotation score: 5 out of 5-Experimental evidence at protein leveli

Functioni

During fertilization, required on male (minus) gametes for their fusion with female (plus) gametes (PubMed:18367645, PubMed:20335357, PubMed:25655701, PubMed:28235200). Required for membrane fusion, but not for the initial adhesion between gametes (PubMed:18367645, PubMed:25655701, PubMed:28235200). Inserts (via its extracellular domain) into lipid membranes (in vitro) (PubMed:28235200). Probably initiates the fusion of gamete cell membranes by inserting its extracellular domain into the cell membrane of a female gamete (PubMed:28235200).4 Publications

Miscellaneous

HAP2/GCS1 family members mediate membrane fusion between gametes in a broad range of eukaryotes, ranging from algae and higher plants to protozoans and cnidaria, suggesting they are derived from an ancestral gamete fusogen (PubMed:20080406). They function similar to viral fusogens, by inserting part of their extracellular domain into the lipid bilayer of an adjoining cell (PubMed:28235200).1 Publication1 Publication

GO - Molecular functioni

  • lipid binding Source: UniProtKB

GO - Biological processi

  • fusion of sperm to egg plasma membrane Source: UniProtKB
  • protein homotrimerization Source: UniProtKB
  • protein insertion into membrane Source: UniProtKB

Keywordsi

Biological processFertilization
LigandLipid-binding

Names & Taxonomyi

Protein namesi
Recommended name:
Hapless 2
Short name:
HAP21 Publication
Alternative name(s):
Generative cell specific-11 Publication
Gene namesi
Name:HAP22 PublicationsImported
Synonyms:GCS11 Publication
OrganismiChlamydomonas reinhardtii (Chlamydomonas smithii)Imported
Taxonomic identifieri3055 [NCBI]
Taxonomic lineageiEukaryotaViridiplantaeChlorophytaChlorophyceaeChlamydomonadalesChlamydomonadaceaeChlamydomonas
Proteomesi
  • UP000006906 Componenti: Unassembled WGS sequence

Subcellular locationi

Topology

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Topological domaini23 – 630ExtracellularCuratedAdd BLAST608
Transmembranei631 – 651HelicalSequence analysisAdd BLAST21
Topological domaini652 – 1139CytoplasmicCuratedAdd BLAST488

GO - Cellular componenti

  • cell projection membrane Source: UniProtKB
  • cytoplasmic vesicle Source: UniProtKB
  • cytoplasmic vesicle membrane Source: UniProtKB-SubCell
  • integral component of plasma membrane Source: UniProtKB

Keywords - Cellular componenti

Cell membrane, Cell projection, Cytoplasmic vesicle, Membrane

Pathology & Biotechi

Disruption phenotypei

No effect on normal adhesion of male (minus) gametes and female (plus) gametes, but the gametes fail to fuse and to give rise to quadriflagellated zygotes.1 Publication

Mutagenesis

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Mutagenesisi184 – 186Missing : No effect on expression at the cell surface. Abolishes ability to mediate gamete fusion. 1 Publication3
Mutagenesisi185 – 186RA → AR: No effect on expression at the cell surface. Abolishes ability to mediate gamete fusion. 1 Publication2
Mutagenesisi185R → A or Q: No effect on expression at the cell surface. Impairs ability to bind to lipid membranes. Abolishes ability to mediate gamete fusion. 1 Publication1
Mutagenesisi185R → K: No effect on expression at the cell surface. No effect on binding to lipid membranes and on ability to mediate gamete fusion. 1 Publication1
Mutagenesisi192 – 193FW → AA: No effect on expression at the cell surface. Nearly abolishes ability to bind lipid membranes. Decreases ability to mediate gamete fusion. 1 Publication2
Mutagenesisi366C → A: Decreases expression at the cell surface. Decreases ability to mediate gamete fusion. 1 Publication1
Mutagenesisi367D → A: No effect on expression at the cell surface. No effect on ability to mediate gamete fusion. 1 Publication1
Mutagenesisi368K → A, M or R: No effect on expression at the cell surface. No effect on ability to mediate gamete fusion. 1 Publication1
Mutagenesisi372G → A: No effect on expression at the cell surface. No effect on ability to mediate gamete fusion. 1 Publication1
Mutagenesisi391L → G: Abolishes expression at the cell surface. Abolishes ability to mediate gamete fusion; when associated with P-394. 1 Publication1
Mutagenesisi394Q → P: Abolishes expression at the cell surface. Abolishes ability to mediate gamete fusion; when associated with G-391. 1 Publication1
Mutagenesisi661 – 662CC → SS: No effect on expression at the cell surface mating structure. Abolishes ability to mediate gamete fusion. 1 Publication2
Mutagenesisi661C → S: No effect on expression at the cell surface mating structure. Slightly decreases ability to mediate gamete fusion. 1 Publication1
Mutagenesisi662C → S: No effect on expression at the cell surface mating structure. No effect on ability to mediate gamete fusion. 1 Publication1

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Signal peptidei1 – 22Sequence analysisAdd BLAST22
ChainiPRO_500266863223 – 1139Hapless 2Add BLAST1117

Amino acid modifications

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Disulfide bondi33 ↔ 44Combined sources1 Publication
Disulfide bondi136 ↔ 164Combined sources1 Publication
Disulfide bondi147 ↔ 210Combined sources1 Publication
Disulfide bondi165 ↔ 383Combined sources1 Publication
Disulfide bondi167 ↔ 190Combined sources1 Publication
Disulfide bondi366 ↔ 390Combined sources1 Publication
Disulfide bondi475 ↔ 482Combined sources1 Publication
Glycosylationi497N-linked (GlcNAc...) asparagineCombined sources1
Disulfide bondi515 ↔ 556Combined sources1 Publication
Glycosylationi577O-linked (GlcNAc...) threonineCombined sources1

Post-translational modificationi

The protein present at the cell membrane is rapidly degraded after fusion between male (minus) and female (plus) gametes, contrary to the protein present in intracellular pools (PubMed:20335357). This may represent a mechanism to avoid fusion of several male gametes with a single female gamete (Probable).Curated1 Publication
N-glycosylated.1 Publication

Keywords - PTMi

Disulfide bond, Glycoprotein

Proteomic databases

PaxDbiA4GRC6.

Expressioni

Developmental stagei

Detected on male (minus) gametes (at protein level) (PubMed:20335357, PubMed:25655701, PubMed:28235200). Detected at low levels in vegetative cells. Highly expressed in male (minus) gametes, with low expression in female (plus) gametes (PubMed:16378100).4 Publications

Interactioni

Subunit structurei

Monomer. Homotrimer. Membrane contact and insertion (via its extracellular domain) into a lipid membrane probably triggers trimerization.1 Publication

Structurei

Secondary structure

11139
Legend: HelixTurnBeta strandPDB Structure known for this area
Show more details
Feature keyPosition(s)DescriptionActionsGraphical viewLength
Beta strandi29 – 36Combined sources8
Turni37 – 39Combined sources3
Beta strandi42 – 54Combined sources13
Beta strandi63 – 68Combined sources6
Beta strandi98 – 105Combined sources8
Beta strandi109 – 112Combined sources4
Beta strandi114 – 122Combined sources9
Beta strandi125 – 129Combined sources5
Beta strandi132 – 134Combined sources3
Turni158 – 161Combined sources4
Beta strandi163 – 165Combined sources3
Helixi185 – 189Combined sources5
Beta strandi207 – 212Combined sources6
Beta strandi217 – 223Combined sources7
Beta strandi227 – 229Combined sources3
Beta strandi232 – 237Combined sources6
Beta strandi285 – 288Combined sources4
Beta strandi296 – 299Combined sources4
Beta strandi302 – 309Combined sources8
Beta strandi322 – 327Combined sources6
Turni347 – 349Combined sources3
Beta strandi352 – 354Combined sources3
Helixi356 – 358Combined sources3
Beta strandi361 – 363Combined sources3
Beta strandi365 – 369Combined sources5
Helixi373 – 376Combined sources4
Beta strandi380 – 382Combined sources3
Helixi389 – 391Combined sources3
Helixi395 – 407Combined sources13
Beta strandi413 – 415Combined sources3
Helixi416 – 418Combined sources3
Turni419 – 421Combined sources3
Helixi425 – 428Combined sources4
Beta strandi437 – 440Combined sources4
Beta strandi447 – 455Combined sources9
Beta strandi458 – 464Combined sources7
Beta strandi467 – 475Combined sources9
Helixi477 – 479Combined sources3
Beta strandi482 – 486Combined sources5
Turni487 – 489Combined sources3
Beta strandi492 – 500Combined sources9
Beta strandi502 – 504Combined sources3
Beta strandi506 – 514Combined sources9
Beta strandi525 – 529Combined sources5
Beta strandi534 – 536Combined sources3
Beta strandi541 – 547Combined sources7
Beta strandi551 – 562Combined sources12
Beta strandi565 – 577Combined sources13

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum
5MF1X-ray3.30A/B/C23-592[»]
SMRiA4GRC6.
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Compositional bias

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Compositional biasi588 – 1124Gly-richPROSITE-ProRule annotationAdd BLAST537
Compositional biasi888 – 905Pro-richPROSITE-ProRule annotationAdd BLAST18
Compositional biasi976 – 990Pro-richPROSITE-ProRule annotationAdd BLAST15

Domaini

Both the cytoplasmic and the extracellular domain are required for normal trafficking to the cell surface, and thus for fertilization (PubMed:25655701). The extracellular domain can insert itself into lipid membranes, probably as a trimer (PubMed:28235200). The extracellular domain has structural similarity to class II viral fusion proteins.2 Publications

Sequence similaritiesi

Belongs to the HAP2/GCS1 family.Curated

Keywords - Domaini

Signal, Transmembrane, Transmembrane helix

Phylogenomic databases

eggNOGiENOG410IX3U. Eukaryota.
ENOG4111J3I. LUCA.

Family and domain databases

InterProiView protein in InterPro
IPR018928. Generative_cell_HAP2/GCS1.
PfamiView protein in Pfam
PF10699. HAP2-GCS1. 1 hit.

Sequencei

Sequence statusi: Complete.

Sequence processingi: The displayed sequence is further processed into a mature form.

A4GRC6-1 [UniParc]FASTAAdd to basket

« Hide

        10         20         30         40         50
MCRAIAVALI VYLAQHYILA HAEVIASGRL EKCVVDGVTE ELDCQEKVVV
60 70 80 90 100
TLTVGNGQSL QTEALEFSLS CLNSPDGRCP CSCSAADPTC ACRDLAAPLR
110 120 130 140 150
VSLTKSPLWA SYPLQYLSSF NWKPLEVILR PSNKVCKDGD WEDSPTCGWF
160 170 180 190 200
SQGGVRVADS QGFCCECSSS QVWDDTFGSS KERTRANLDC DFWSDPLDIL
210 220 230 240 250
IGRKPVSAHC LTFDPQWYSG YELGAASLQF EIAITVEVPT APSPTTATTS
260 270 280 290 300
ATPRTNNSSS ANSTNSTNSP APQFLSPPAP STREVLHLGP SVPLASSASR
310 320 330 340 350
LLSAKLLGDL AMYTQLPAIS NQVLMVPQPP AAAAATGSPL DATLATNRSA
360 370 380 390 400
WMLLDKTMLS MDGLACDKVG TGFSAFRYQP SGCGRAPQAC LSGQLKDLWE
410 420 430 440 450
ADLARIADGR VPLYMITRFT GGSDTTLQSF SGGPLSFALP VTSHSQSLVT
460 470 480 490 500
LSVAADGVRL VTNRSPGKIT GAAVCRFAGT SCGGFEAVAA RGYIYVNITN
510 520 530 540 550
TGRLDSDYTL TVSNCSSNVR PIEARTLAVR AGSAASLDPP MELYVEDQAA
560 570 580 590 600
AAARTCTVSL YDSVGAVTDS LTLSFYTNAT QLVVKPSGGY NGTGDGAGVK
610 620 630 640 650
RNGTDCSTAC TNPIDVLCFV TKKCWSKFGR LLGIIGGALV GLGLLAVALK
660 670 680 690 700
FGWLASLAAS CCGGGGGAAA GGAGGGMGLG TGGGGGCFGG GQQQQQLPPA
710 720 730 740 750
ASHAMSPPQQ QQRSHAEVAA GAAVAGAGAA GAAAAVLGAK HGGGGGGARG
760 770 780 790 800
KQQHADTRHL QDRDSRAIDG GASIGSSSAG GSSSLSSYSQ PREAGGRLLQ
810 820 830 840 850
PPAAAVFVPE GGGGGAAGDE GARAQSSDWD ARGRSPRVAD EHGSPRQRYD
860 870 880 890 900
GVRQSPYMVS ANPYDGWYDG GSGGGGGGGG GGYGREAPPP QGPPPHPVGA
910 920 930 940 950
PPPPPRRRSL WERMWLQRPG GGGGGGGGGG GGGGGGSGGG VDQHGGRSCA
960 970 980 990 1000
DAARRGGGGP GGMRGVEGLM SNGGRPNGPH PHAPPPPPPP QQQQQQQRQR
1010 1020 1030 1040 1050
RSFLESLTAM MTLPWGGGRE EEAGGDRRGG GRGGAAAAHG GRGAGGGRGH
1060 1070 1080 1090 1100
PPSIGSPPPG PLQPPEYGPQ GGQARRWGAG GGRGGVGGDG GGGGVGAAAY
1110 1120 1130
VQLSTGGRGG GGGGGRGRGG GREGPTWHNP VYDWQAPPK
Length:1,139
Mass (Da):115,204
Last modified:March 23, 2010 - v2
Checksum:i10686ACC371BBE93
GO

Experimental Info

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Sequence conflicti697L → Q in BAE71145 (PubMed:16378100).Curated1
Sequence conflicti708P → PQ in BAE71145 (PubMed:16378100).Curated1
Sequence conflicti731G → V in BAE71145 (PubMed:16378100).Curated1
Sequence conflicti747G → A in BAE71145 (PubMed:16378100).Curated1

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
EF397563 mRNA. Translation: ABO29824.2.
DS496135 Genomic DNA. No translation available.
AB206813 mRNA. Translation: BAE71145.2.

Similar proteinsi

Entry informationi

Entry nameiHAP2_CHLRE
AccessioniPrimary (citable) accession number: A4GRC6
Secondary accession number(s): Q2PGG4
Entry historyiIntegrated into UniProtKB/Swiss-Prot: May 10, 2017
Last sequence update: March 23, 2010
Last modified: July 5, 2017
This is version 25 of the entry and version 2 of the sequence. See complete history.
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programPlant Protein Annotation Program

Miscellaneousi

Keywords - Technical termi

3D-structure, Complete proteome, Reference proteome

Documents

  1. PDB cross-references
    Index of Protein Data Bank (PDB) cross-references
  2. SIMILARITY comments
    Index of protein domains and families