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. Author manuscript; available in PMC: 2020 Aug 26.
Published in final edited form as: Annu Rev Genet. 2019 Jul 5;53:67–91. doi: 10.1146/annurev-genet-120116-024603

Table 1.

Molecular components of myoblast fusion

Fusion regulator Protein type Cell type Localization at fusogenic synapse Function in myoblast fusion Reference(s)
Duf/Kirre Ig domain–containing CAM FC Ring-like structure Promotes FC–FCM adhesion and binds to Sns and Hbs in tram to establish fusogenic synapse 104, 121
Rst Ig domain–containing CAM FC ND Promotes FC–FCM adhesion and binds to Sns and Hbs in tram to establish fusogenic synapse 121
Sns Ig domain–containing CAM FCM Ring-like structure Promotes FC–FCM adhesion and binds to Duf and Rst in tram to establish fusogenic synapse 18, 106
Hbs Ig domain–containing CAM FCM ND Promotes FC–FCM adhesion and binds to Duf and Rst in tram to establish fusogenic synapse 5, 48
Sing Multipass transmembrane protein ND ND Potentially involved in vesicle trafficking 51
Rols7/Ants Ankyrin repeat-, tetratricopeptide repeat-, and coiled-coil domain–containing protein FC Ring-like structure Replenishes Duf at the fusogenic synapse by vesicle trafficking 27, 85, 99
Dock SH2 and SH3 domain–containing adaptor protein ND ND Links CAMs and actin cytoskeletal regulators 74
Drk SH2 and SH3 domain–containing adaptor protein ND ND Links CAMs and actin cytoskeletal regulators 74
Crk SH2 and SH3 domain–containing adaptor protein ND ND Links CAMs and actin cytoskeletal regulators 7, 73, 79
Sltr/WIP WASP-binding protein FCM Actin focus Recruits WASP to the fusogenic synapse 79, 84
WASP Actin NPF FCM Actin focus Promotes branched actin polymerization; required for actin foci formation and membrane protrusion generation 12, 59, 79, 84, 108, 114
Blow PH domain–containing protein FCM Actin focus Competes with WASP for WIP binding to destabilize the WASP-WIP complex 38, 73
Mbc Bipartite Rac GEF FCM Actin focus Activates Rac proteins together with Elmo 50, 66, 106
Elmo Bipartite Rac GEF FCM Actin focus Activates Rac proteins together with Mbc 58
Rac1 Small G protein FCM Actin focus Activates Scar complex and group I Pak together with Rac2 63, 82
Rac2 Small G protein FCM Actin focus Activates Scar complex and group I Pak together with Rac1 63, 82
Scar/WAVE Actin NPF FCM, FC Actin focus Promotes branched actin polymerization; required for actin foci formation in FCMs and actin sheath formation in FCs 12, 59, 100, 114
Kette Component of the SCAR complex FCM, FC Actin focus Stabilizes the Scar complex; not required for membrane protrusion generation 65, 73, 111, 114
Arp3 Component of the Arp2/3 actin nucleator FCM, FC Actin focus Promotes nucleation of branched actin filament 12, 100
ArpC1 Component of the Arp2/3 actin nucleator FCM, FC Actin focus Promotes nucleation of branched actin filament 84
DPak3 Serine/threonine kinase FCM Actin focus Promotes invasive protrusions with DPak1 44
DPak1 Serine/threonine kinase FCM Actin focus Promotes invasive protrusions with DPak3 44
Loner/Schizo Arf GEF FCM, FC Actin focus Activates Arf proteins 22, 29
Arf1 Small G protein ND ND Regulates N-Cad 42
Arf6 Small G protein ND ND Regulates Rac localization 29, 42
Rho1 Small G protein FC Actin sheath Activates Rok 78
Rok Serine/threonine kinase FC Actin sheath Phosphoactivates and activates MyoII 78
Nonmuscle MyoII Actin motor FC Actin sheath Mechanosensor; increases cortical tension via actomyosin contraction 78
βH-Spectrin Spectrin cytoskeleton subunit FC Actin sheath Mechanoresponsive as a heterotetramer with α-spectrin; restricts Duf at the fusogenic synapse; constricts FCM protrusions 45
α-Spectrin Spectrin cytoskeleton subunit FC Actin sheath Mechanoresponsive as a heterotetramer with βH-spectrin; restricts Duf at the fusogenic synapse; constricts FCM protrusions 45
PIP2 Phospholipid FCM, FC Enriched on membrane Controls localization of actin regulators at the fusogenic synapse 17
Dia Actin NPF FCM? Actin focus ND 34
D-Titin Giant filamentous protein FCM? Actin focus ND 83, 85, 131
WHAMY Actin NPF ND ND ND 20
Rab11 Small G protein ND ND ND 13

Abbreviations: βH-spectrin, βHeavy-spectrin; Ants, Antisocial; Arf1, ADP-ribosylation factor 1; Arf6, ADP-ribosylation factor 6; Arp3, Actin-related protein 3; ArpC1, Actin-related protein C1; Blow, Blown fuse; CAM, cell adhesion molecule; Crk, Crk oncogene; Dia, Diaphanous; Dock, Dreadlocks; DPak1, Drosophila p21-activated kinase 1; DPak3, Drosophila p21-activated kinase 3; Drk, Downstream of receptor kinase; Duf, Dumbfounded; Elmo, Engulfment and cell motility protein; FC, founder cell; FCM, fusion-competent myoblast; GEF, guanine nucleotide exchange factor; Hbs, Hibris; Ig, immunoglobulin; Mbc, Myoblast city; MyoII, myosin II; ND, not determined; NPF, nucleation-promoting factor; PH, pleckstrin homology; PIP2, phosphatidylinositol 4,5-bisphosphate; Rok, Rho kinase; Rols7, Rolling pebbles 7; Rst, Roughest; Scar, Suppresser of cAMP receptor; Sing, Singles bar; Sltr, Solitary; Sns, Sticks and stones;WASP,Wiskott–Aldrich syndrome protein;WAVE,WASP family verprolin homologs; WIP,WASP-interacting protein.