module: dmel_irm_myoblast_adhesion
title: IRM adhesion complexes in Drosophila melanogaster
label: IRM adhesion complexes
module_type: BIOLOGICAL_PROCESS
description: >-
  The IRM (Irre cell recognition module) proteins are four immunoglobulin-
  superfamily adhesion receptors that bind each other in trans between neighbouring
  cells. Kin of irre (Kirre, also called Dumbfounded) and Roughest (Rst) form one
  pair of paralogs, and Sticks and stones (Sns) and Hibris (Hbs) the other; each
  Kirre/Rst protein can bind each Sns/Hbs protein. In the embryonic mesoderm, Kirre
  and Rst on founder cells bind Sns and Hbs on fusion-competent myoblasts to
  attract them and initiate myoblast fusion. The same heterophilic pairs pattern the
  interommatidial cells of the eye and, in nephrocytes, Sns and Kirre form the slit
  diaphragm.
summary: >-
  Trans-binding Kirre/Rst and Sns/Hbs immunoglobulin-superfamily receptor pairs that
  mediate myoblast recognition and fusion and other cell-sorting events.
concepts:
  - {id: GO:0007520, label: myoblast fusion}
  - {id: GO:0098609, label: cell-cell adhesion}
variant_sets:
  - id: irm_pairs
    label: Heterophilic IRM receptor pairs
    selection: ONE_OR_MORE
    variants:
      - {id: kirre_sns, label: Sns-Kirre adhesion complex, group: SK-CAM, complex: true, unit_functions: {sns: {id: GO:0098631, label: cell adhesion mediator activity}, hbs: {id: GO:0098631, label: cell adhesion mediator activity}}}
      - {id: kirre_hbs, label: Hbs-Kirre adhesion complex, group: HK-CAM, complex: true, unit_functions: {sns: {id: GO:0098631, label: cell adhesion mediator activity}, hbs: {id: GO:0098631, label: cell adhesion mediator activity}}}
      - {id: rst_sns, label: Rst-Sns adhesion complex, group: RS-CAM, complex: true, unit_functions: {sns: {id: GO:0098631, label: cell adhesion mediator activity}, hbs: {id: GO:0098631, label: cell adhesion mediator activity}}}
      - {id: rst_hbs, label: Hbs-Rst adhesion complex, group: HR-CAM, complex: true, unit_functions: {sns: {id: GO:0098631, label: cell adhesion mediator activity}, hbs: {id: GO:0098631, label: cell adhesion mediator activity}}}
notes: >-
  Each pair is formed in trans between a Kirre/Rst protein on one cell and an
  Sns/Hbs protein on the neighbouring cell, so each gene appears in two of the four pairs. Downstream fusion machinery
  (for example the WAVE and WASp Arp2/3 activators and their adaptors) is context
  and not part of this module. The contribution of each pair differs between
  tissues; in myoblast fusion Kirre and Rst act redundantly in founder cells, and
  Sns has the major role in fusion-competent myoblasts. Sns and Hbs are given
  cell adhesion mediator activity (GO:0098631), which both carry in GOA by
  IPI; Kirre and Rst carry only cell adhesion molecule binding terms and are
  left without an annoton function.
group: IRM-CAM