FB2026_03 , released September 17, 2026
Physical Interaction report
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General Information
Interaction Type
Interacting Genes
FlyBase ID
FBig0000102949
Interaction Network
Interactions Browser links
Irbp18 network
Xrp1 network
Reported Interactions
FBrf0227576-28.FRET
Description
physical association
Collection
Source/Stage
Cell line used
Participants
Corresponds to
Reported as
Role
Note

DM10

fluorescence donor

fluorescein label

DM10

fluorescence donor

fluorescein label

DM10

fluorescence donor

fluorescein label

Xrp1 

DM28

fluorescence acceptor

TAMRA label

Xrp1 
Xrp1 

DM28

fluorescence acceptor

TAMRA label

Xrp1 

DM28

fluorescence acceptor

TAMRA label

Xrp1 
Experimental entities
Corresponds to
Identifier
Reported
Role
Note
Subregions with role in interaction
Corresponds to
Description
Role
Coordinates
Note
bZIP domain
sufficient binding region
DSPLSPHTDDPAYKEKRKKNNEAVQRTREKTKKSAEERKKRIDDLRKQNDALKVQIETSEKHISTLRDLII
Xrp1 
bZIP domain
sufficient binding region
LMSSMKSEEERKAYQDRLKNNEASRVSRRKTKVREEEEKRAEDTLLAENLRLRARADEVASRERKFKKYLM
Isoform-specific participants
Corresponds to
Description
Role
Note
Comments concerning this interaction

Interaction in vitro; fluorescence donor produced as a recombinant fusion protein in bacterial system and labeled in vitro; fluorescence acceptor produced as a recombinant fusion protein in bacterial system and labeled in vitro.

Dissociation constant of Kd=233nM.

Interactions between bZIP proteins were quantified in vitro using a solution FRET assay at 4oC, 21oC and 37oC. Only interactions at 21oC with Kd < 5000 nm were curated by FlyBase.

FBrf0227576-64.FRET
Description
physical association
Collection
Source/Stage
Cell line used
Participants
Corresponds to
Reported as
Role
Note
Xrp1 

DM28

fluorescence donor

fluorescein label

Xrp1 

DM28

fluorescence donor

fluorescein label

Xrp1 
Xrp1 

DM28

fluorescence donor

fluorescein label

Xrp1 

DM10

fluorescence acceptor

TAMRA label

DM10

fluorescence acceptor

TAMRA label

DM10

fluorescence acceptor

TAMRA label

Experimental entities
Corresponds to
Identifier
Reported
Role
Note
Subregions with role in interaction
Corresponds to
Description
Role
Coordinates
Note
Xrp1 
bZIP domain
sufficient binding region
LMSSMKSEEERKAYQDRLKNNEASRVSRRKTKVREEEEKRAEDTLLAENLRLRARADEVASRERKFKKYLM
bZIP domain
sufficient binding region
DSPLSPHTDDPAYKEKRKKNNEAVQRTREKTKKSAEERKKRIDDLRKQNDALKVQIETSEKHISTLRDLII
Isoform-specific participants
Corresponds to
Description
Role
Note
Comments concerning this interaction

Interaction in vitro; fluorescence donor produced as a recombinant fusion protein in bacterial system and labeled in vitro; fluorescence acceptor produced as a recombinant fusion protein in bacterial system and labeled in vitro.

Dissociation constant of Kd=510nM.

Interactions between bZIP proteins were quantified in vitro using a solution FRET assay at 4oC, 21oC and 37oC. Only interactions at 21oC with Kd < 5000 nm were curated by FlyBase.

FBrf0234070-1.coIP.MS
Description
physical association
Collection
Source/Stage
Cell line used
Participants
Corresponds to
Reported as
Role
Note

IRBP18

bait

Protein A tag, FLAG tag

Xrp1 

Xrp1

prey
Experimental entities
Corresponds to
Identifier
Reported
Role
Note
Subregions with role in interaction
Corresponds to
Description
Role
Coordinates
Note
Isoform-specific participants
Corresponds to
Description
Role
Note
Comments concerning this interaction

Source was cell extract of S2 cell line; bait produced from transfected construct; prey produced from endogenous gene.

FBrf0234070-2.CH.WB
Description
physical association
Collection
Source/Stage
Cell line used
Participants
Corresponds to
Reported as
Role
Note

IRBP18

neutral component

IRBP18

neutral component

IRBP18

neutral component
Xrp1 

Xrp1

neutral component
Xrp1 

Xrp1

neutral component
Xrp1 

Xrp1

neutral component
Experimental entities
Corresponds to
Identifier
Reported
Role
Note
Subregions with role in interaction
Corresponds to
Description
Role
Coordinates
Note
Isoform-specific participants
Corresponds to
Description
Role
Note
Comments concerning this interaction

CG6272 and Xrp1 copurify from Kc nuclear extracts through several chromatographic steps.

Source was nuclear extract of Kc cell line; bait produced from endogenous gene; prey produced from endogenous gene.

FBrf0234070-3.PD.MW
Description
physical association
Collection
Source/Stage
Cell line used
Participants
Corresponds to
Reported as
Role
Note
Xrp1 

Xrp1

bait

His tag

IRBP18

prey

FLAG tag

Experimental entities
Corresponds to
Identifier
Reported
Role
Note
Subregions with role in interaction
Corresponds to
Description
Role
Coordinates
Note
Isoform-specific participants
Corresponds to
Description
Role
Note
Comments concerning this interaction

Interaction in vitro; bait produced as a recombinant fusion protein in bacterial system; prey produced as a recombinant fusion protein in bacterial system.

FBrf0241977-2089.BiFC.FM
Description
physical association
Collection
Cell line used
Participants
Corresponds to
Reported as
Role
Note

Irbp18

unspecified role

Irbp18

unspecified role

Irbp18

unspecified role
Xrp1 

Xrp1

unspecified role
Xrp1 

Xrp1

unspecified role
Xrp1 

Xrp1

unspecified role
Experimental entities
Corresponds to
Identifier
Reported
Role
Note
Subregions with role in interaction
Corresponds to
Description
Role
Coordinates
Note
Isoform-specific participants
Corresponds to
Description
Role
Note
Comments concerning this interaction

Source was larval eye discs of transgenic fly line; proteins produced from tagged transgenic construct.

FBrf0241977-968.Y2H
Description
physical association
Collection
Source/Stage
Cell line used
Participants
Corresponds to
Reported as
Role
Note

Irbp18

bait

fused to GAL4 DNA-binding domain

Xrp1 

Xrp1

prey

fused to GAL4 activation domain

Experimental entities
Corresponds to
Identifier
Reported
Role
Note
Subregions with role in interaction
Corresponds to
Description
Role
Coordinates
Note
Isoform-specific participants
Corresponds to
Description
Role
Note
Comments concerning this interaction

Source was yeast cell line; bait produced as transgenic fusion protein; prey produced as transgenic fusion protein (prey was previously cloned reagent).

Two-hybrid system: yeast GAL4-BD/GAL4-AD

External Crossreferences and Linkouts ( 1 )
Linkouts
MIST - An integrated Molecular Interaction Database
References (3)