| Protein . | Family . | Organism . | Suggested fusion event . | Fusogenic scorea . | Essential for fusion (0–2) . | Structural similarity to fusogens (0–2) . | Expressed at the time and place of fusion (0–2) . | Sufficiency (0–4)b . | References . | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| . | . | . | . | . | . | . | . | A . | B . | C . | D . | . |
| HA | Class I viral fusogens | Influenza virus | Viral infection | 10 | + | + | + | + | + | + | + | Reviewed in Kielian and Rey, 2006 |
| p14 | FAST proteins (Class IV viral fusogens) | Reptilian orthoreoviruses | Infected cells | 10 | + | + | + | + | + | + | + | Reviewed in Key and Duncan, 2014 |
| E1 | Fusexins (Class II viral fusogens) | Semliki Forest virus | Viral infection | 9.5 | + | + | + | + | + | + | ± | Reviewed in Kielian and Rey, 2006 |
| vSNARES, tSNARES | SNAREs (endoplasmic fusogens) | Eukaryotes and Archaea | Intracellular vesicles | 9 | + | + | + | + | + | ND | + | Reviewed in Jahn and Scheller, 2006 |
| EFF-1 | Fusexins (FF) | C. elegans; Nematodes | Epithelia, vulva, pharynx, axons | 9 | + | + | + | + | + | + | ND | Mohler et al., 2002; Shemer et al., 2004; Podbilewicz et al., 2006; Avinoam et al., 2011 |
| Syncytins | Class I viral fusogens | Placental mammals | Placenta, osteoclasts, myoblasts, cancer cells | 9 | + | + | + | + | + | + | ND | Blond et al., 2000; Mi et al., 2000; Bjerregaard et al., 2006; Antony et al., 2007; Dupressoir et al., 2011; Søe et al., 2011 |
| Atlastins | Dynamin (endoplasmic fusogen) | Eukaryotes | Endoplasmic reticulum | 8 | + | + | + | + | ND | ND | + | Reviewed in Hu and Rapoport, 2016 |
| HAP2/GCS1 | Fusexins (HAP2) | Arabidopsis; plants | Fertilization (sperm) | 8 | + | + | + | ND | + | + | ND | Mori et al., 2006; von Besser et al., 2006; Valansi et al., 2017 |
| AFF-1 | Fusexins (FF) | C. elegans; Nematodes | Epithelia, vulva, pharynx, dendrites | 8 | + | ± | + | + | + | + | ND | Sapir et al., 2007; Avinoam et al., 2011 |
| Myomaker | Multi-pass transmembrane protein | Mus musculus; Human | Myoblasts | 6 | + | ND | + | + | + | ND | ND | Millay et al., 2013; Bi et al., 2017; Gamage et al., 2017; Quinn et al., 2017; Zhang et al., 2017a; Leikina et al., 2018 |
| Myomerger | Single-pass transmembrane protein | |||||||||||
| HAP2/GCS1 | Fusexins (HAP2) | T. thermophila; Trypanosomes | Mating | 6 | + | + | + | ND | ND | ND | ND | Pinello et al., 2017 |
| HAP2/GCS1 | Fusexins (HAP2) | Chlamydomonas; Algae | Fertilization (mt− cell) | 6 | + | + | + | ND | ND | ND | ND | Liu et al., 2008; Fédry et al., 2017 |
| Bouncer | Ly6/uPAR | Danio reri and Oryzias latipes | Fertilization (egg) | 5 | + | − | + | + | ND | ND | ND | Herberg et al., 2018 |
| Izumo1 | IgSF | M. musculus; Mammals | Fertilization (sperm) | 4 | + | − | + | − | − | ND | ND | Inoue et al., 2005, 2013, 2015; Chalbi et al., 2014 |
| Juno | Folate receptors | M. musculus; Mammals | Fertilization (oocyte) | 4 | + | − | + | − | − | ND | ND | Bianchi et al., 2014; Kato et al., 2016 |
| SPE-9 | EGF repeats | C. elegans; Nematodes | Fertilization (sperm) | 4 | + | ND | + | ND | ND | ND | ND | Singson et al., 1998 |
| Sns | IgSF | Drosophila | FCM | 4 | + | ND | + | − | − | ND | ND | Bour et al., 2000; Shilagardi et al., 2013 |
| Duf/Kirre | IgSF | Drosophila | FC | 4 | + | ND | + | − | − | ND | ND | Ruiz-Gómez et al., 2000; Shilagardi et al., 2013 |
| Bindin | Bindins | S. purpuratus; Sea urchins | Fertilization (sperm) | 3 | ND | ND | + | ND | ND | ND | + | Vacquier and Moy, 1977; Glabe, 1985; Vacquier, 2012 |
| PRM1 | Tetraspanin integral protein | S. cerevisiae; Yeast | Mating | 3 | ± | ND | + | − | ND | ND | ND | Heiman and Walter, 2000; Olmo and Grote, 2010 |
| Protein . | Family . | Organism . | Suggested fusion event . | Fusogenic scorea . | Essential for fusion (0–2) . | Structural similarity to fusogens (0–2) . | Expressed at the time and place of fusion (0–2) . | Sufficiency (0–4)b . | References . | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| . | . | . | . | . | . | . | . | A . | B . | C . | D . | . |
| HA | Class I viral fusogens | Influenza virus | Viral infection | 10 | + | + | + | + | + | + | + | Reviewed in Kielian and Rey, 2006 |
| p14 | FAST proteins (Class IV viral fusogens) | Reptilian orthoreoviruses | Infected cells | 10 | + | + | + | + | + | + | + | Reviewed in Key and Duncan, 2014 |
| E1 | Fusexins (Class II viral fusogens) | Semliki Forest virus | Viral infection | 9.5 | + | + | + | + | + | + | ± | Reviewed in Kielian and Rey, 2006 |
| vSNARES, tSNARES | SNAREs (endoplasmic fusogens) | Eukaryotes and Archaea | Intracellular vesicles | 9 | + | + | + | + | + | ND | + | Reviewed in Jahn and Scheller, 2006 |
| EFF-1 | Fusexins (FF) | C. elegans; Nematodes | Epithelia, vulva, pharynx, axons | 9 | + | + | + | + | + | + | ND | Mohler et al., 2002; Shemer et al., 2004; Podbilewicz et al., 2006; Avinoam et al., 2011 |
| Syncytins | Class I viral fusogens | Placental mammals | Placenta, osteoclasts, myoblasts, cancer cells | 9 | + | + | + | + | + | + | ND | Blond et al., 2000; Mi et al., 2000; Bjerregaard et al., 2006; Antony et al., 2007; Dupressoir et al., 2011; Søe et al., 2011 |
| Atlastins | Dynamin (endoplasmic fusogen) | Eukaryotes | Endoplasmic reticulum | 8 | + | + | + | + | ND | ND | + | Reviewed in Hu and Rapoport, 2016 |
| HAP2/GCS1 | Fusexins (HAP2) | Arabidopsis; plants | Fertilization (sperm) | 8 | + | + | + | ND | + | + | ND | Mori et al., 2006; von Besser et al., 2006; Valansi et al., 2017 |
| AFF-1 | Fusexins (FF) | C. elegans; Nematodes | Epithelia, vulva, pharynx, dendrites | 8 | + | ± | + | + | + | + | ND | Sapir et al., 2007; Avinoam et al., 2011 |
| Myomaker | Multi-pass transmembrane protein | Mus musculus; Human | Myoblasts | 6 | + | ND | + | + | + | ND | ND | Millay et al., 2013; Bi et al., 2017; Gamage et al., 2017; Quinn et al., 2017; Zhang et al., 2017a; Leikina et al., 2018 |
| Myomerger | Single-pass transmembrane protein | |||||||||||
| HAP2/GCS1 | Fusexins (HAP2) | T. thermophila; Trypanosomes | Mating | 6 | + | + | + | ND | ND | ND | ND | Pinello et al., 2017 |
| HAP2/GCS1 | Fusexins (HAP2) | Chlamydomonas; Algae | Fertilization (mt− cell) | 6 | + | + | + | ND | ND | ND | ND | Liu et al., 2008; Fédry et al., 2017 |
| Bouncer | Ly6/uPAR | Danio reri and Oryzias latipes | Fertilization (egg) | 5 | + | − | + | + | ND | ND | ND | Herberg et al., 2018 |
| Izumo1 | IgSF | M. musculus; Mammals | Fertilization (sperm) | 4 | + | − | + | − | − | ND | ND | Inoue et al., 2005, 2013, 2015; Chalbi et al., 2014 |
| Juno | Folate receptors | M. musculus; Mammals | Fertilization (oocyte) | 4 | + | − | + | − | − | ND | ND | Bianchi et al., 2014; Kato et al., 2016 |
| SPE-9 | EGF repeats | C. elegans; Nematodes | Fertilization (sperm) | 4 | + | ND | + | ND | ND | ND | ND | Singson et al., 1998 |
| Sns | IgSF | Drosophila | FCM | 4 | + | ND | + | − | − | ND | ND | Bour et al., 2000; Shilagardi et al., 2013 |
| Duf/Kirre | IgSF | Drosophila | FC | 4 | + | ND | + | − | − | ND | ND | Ruiz-Gómez et al., 2000; Shilagardi et al., 2013 |
| Bindin | Bindins | S. purpuratus; Sea urchins | Fertilization (sperm) | 3 | ND | ND | + | ND | ND | ND | + | Vacquier and Moy, 1977; Glabe, 1985; Vacquier, 2012 |
| PRM1 | Tetraspanin integral protein | S. cerevisiae; Yeast | Mating | 3 | ± | ND | + | − | ND | ND | ND | Heiman and Walter, 2000; Olmo and Grote, 2010 |
The fusogenic score (0–10) was calculated using the following scoring system: + (requirement fulfilled) = max score, − (requirement not fulfilled) = 0 points, ND (not determined) = 0 points, and ± (requirement partially fulfilled) = half of max score.
The fusogenic score (0–10).
(A) Sufficient in situ (0–1). (B) Fuse heterologous cells (0–1). (C) Fuse pseudo-typed virus (0–1). (D) In vitro liposome fusion (0–1).