title: Functional conservation study of polarity protein Crumbs intracellular domain.
abstract: The transmembrane protein Crumbs (Crb) plays key roles in the establishing and maintaining cell apical-basal polarity in epithelial cells by determining the apical plasma membrane identity. Although its intracellular domain contains only 37 amino acids, it is absolutely essential for its function. In Drosophila, mutations in this intracellular domain result in severe defects in epithelial polarity and abnormal embryonic development. The intracellular domain of Crb shows high homology across species from Drosophila to Mus musculus and Homo sapiens. However, the intracellular domains of the two Crb proteins in C. elegans are rather divergent from those of Drosophila and mammals, raising the question on whether the function of the intracellular domain of the Crb protein is conserved in C. elegans. Using genomic engineering approach, we replaced the intracellular domain of the Drosophila Crb with that of C. elegans Crb2 (CeCrb2), which has extremely low homology with those from the Crb proteins of Drosophila and mammals. Surprisingly, substituting the intracellular domain of Drosophila Crb with that of CeCrb2 did not cause any abnormalities in development of the Drosophila embryo, in terms of expression and localization of Crb and other polarity proteins and apical-basal polarity in embryonic epithelial cells. Our results support the notion that despite their extensive sequence variations, all functionally critical amino acid residues and motifs of the intercellular domain of Crb proteins are fully conserved between Drosophila and C. elegans.
authors.affiliation: School of Basic Medical Sciences, Nanjing Medical University, Nanjing 211166, China.
authors.forename: Qi-ping
authors.initials: QP
authors.lastname: Shi
authors.affiliation: School of Basic Medical Sciences, Nanjing Medical University, Nanjing 211166, China.
authors.forename: Hao-wei
authors.initials: HW
authors.lastname: Cao
authors.affiliation: School of Basic Medical Sciences, Nanjing Medical University, Nanjing 211166, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Xu
authors.affiliation: School of Basic Medical Sciences, Nanjing Medical University, Nanjing 211166, China.
authors.forename: Dan-dan
authors.initials: DD
authors.lastname: Zhang
authors.affiliation: School of Basic Medical Sciences, Nanjing Medical University, Nanjing 211166, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Huang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics; D002462:Cell Membrane / Q000235:genetics; D016764:Cell Polarity / Q000235:genetics*; D003593:Cytoplasm / Q000235:genetics; D004330:Drosophila / Q000235:genetics; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics; D051379:Mice; D000072417:Protein Domains / Q000235:genetics*
chemical_list: D008565:Membrane Proteins