Mutations in the Drosophila alphaPS2 integrin subunit uncover new features of adhesion site assembly.
The Drosophila alphaPS2betaPS integrin is required for diverse development events, including muscle attachment. We characterized six unusual mutations in the alphaPS2 gene that cause a subset of the null phenotype. One mutation changes a residue in alphaPS2 that is equivalent to the residue in alphaV that contacts the arginine of RGD. This change severely reduced alphaPS2betaPS affinity for soluble ligand, abolished the ability of the integrin to recruit laminin to muscle attachment sites in the embryo and caused detachment of integrins and talin from the ECM. Three mutations that alter different parts of the alphaPS2 beta-propeller, plus a fourth that eliminated a late phase of alphaPS2 expression, all led to a strong decrease in alphaPS2betaPS at muscle ends, but, surprisingly, normal levels of talin were recruited. Thus, although talin recruitment requires alphaPS2betaPS, talin levels are not simply specified by the amount of integrin at the adhesive junction. These mutations caused detachment of talin and actin from integrins, suggesting that the integrin-talin link is weaker than the ECM-integrin link.
Devenport
Danelle
D
The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK.
Bunch
Thomas A
TA
Bloor
James W
JW
Brower
Danny L
DL
Brown
Nicholas H
NH
D000199:Actins / Q000378:metabolism; D022005:Adherens Junctions / Q000235:genetics / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D004330:Drosophila / Q000196:embryology / Q000235:genetics* / Q000502:physiology*; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D005109:Extracellular Matrix / Q000502:physiology; D017344:Genes, Insect; D039001:Integrin alpha Chains / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D008024:Ligands; D008297:Male; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D008969:Molecular Sequence Data; D024510:Muscle Development / Q000235:genetics / Q000502:physiology; D009154:Mutation; D010641:Phenotype; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D016608:Talin / Q000378:metabolism
D000199:Actins; D029721:Drosophila Proteins; D039001:Integrin alpha Chains; D008024:Ligands; D016608:Talin; C082188:if protein, Drosophila