Mutational and secondary structural analysis of the basolateral sorting signal of the polymeric immunoglobulin receptor.

Abstract

Abstract. The 17-juxtamembrane cytoplasmic residues of the polymeric immunoglobulin receptor contain an autonomous basolateral targeting signal that does not mediate rapid endocytosis (Casanova, J. E., G. Apodaca, and K. E. . Alanine-scanning mutagenesis identifies three residues in this region, His656, Arg657, and Va1660, that are most essential for basolateral sorting and two residues, Arg655 and Tyr668, that play a lesser role in this process. Progressive truncations suggested that Ser664 and Ile665 might also play a role in basolateral sorting. However, mutation of these residues to Ala or internal deletions of these residues did not affect basolateral sorting, indicating that these residues are probably not required for basolateral sorting. Twodimensional NMR spectroscopy of a peptide corresponding to the 17-mer signal indicates that the sequence Arg658-Asn-Val-Asp661 has a propensity to adopt a/if-turn in solution. Residues COOH-terminal to the B-turn (Arg662 to Arg669) seem to take up a nascent helix structure in solution. Substitution of Va1660 with Ala destabilizes the turn, while mutation of Arg657 to Ala does not appear to affect the turn structure. Neither mutation detectably altered the stability of the nascent helix in the COOH-terminal portion of the peptide.p OLARIZED epithelial cells have two plasma membrane domains: the apical domain facing the external environment, and the basolateral domain facing the internal milieu. These domains display striking differences in protein and lipid composition (Caplan and Matlin, 1989;

Protein kinase D regulates basolateral membrane protein exit from trans-Golgi network

“…For basolateral proteins, adaptor protein complexes AP-1B 9 and AP-4 (ref. 10) might be involved in sorting proteins in the TGN and/or endosomes [11][12][13] . Transport from the TGN to the apical plasma membrane is dependent on dynamin and a kinesin-like motor protein 14 .…”

Calmodulin Binds to the Basolateral Targeting Signal of the Polymeric Immunoglobulin Receptor

“…A construct encoding the full-length pIgR molecule with a substitution of alanine for arginine at position 658 was constructed by ligating a DNA fragment encoding the C terminus (residues 661-755) of wild-type pIgR clone to a fragment encoding residues 1-660 derived from the R658A/T670-STOP mutant described previously (4) via a common AvaII site at nucleotide position 2007. The resulting cDNA was ligated into the BglII site of pCB6 (36) and transfected into MDCK strain II cells as described previously (4). Mutants in which serine 664 has been mutated to alanine (S664A) or aspartic acid (S664D) have also been described (7).…”

“…Mutation of other residues had little or no effect. The structure of a synthetic 17-residue peptide corresponding to this signal has been determined by two-dimensional nuclear magnetic resonance spectroscopy (4). This peptide tends to adopt a putative type 1 ␤-turn, encompassing residues 658 -661, followed by a nascent helical structure.…”

“…The pIgR basolateral targeting signal has been systematically analyzed by alanine scanning mutagenesis (4). Mutation of His-656, Arg-657, or Val-660 to Ala substantially diminishes, but does not eliminate, TGN to basolateral targeting.…”

Involvement of the cytoplasmic juxtamembrane region of matriptase in its exclusive localization to the basolateral membrane domain of Madin–Darby canine kidney epithelial cells

“…Lys45 and Val47 are part of sequence KQVE, resembling sequence RNVD in the 17-amino-acid juxtamembrane region (cytoplasmic region) of the polymeric immunoglobulin receptor (pIgR), in which the valine residue (Val660) is the critical residue for basolateral sorting ( Fig. 4; Aroeti et al 1993). Furthermore, basic amino acids within the 17-amino-acid region (His656 and Arg657) also contribute to basolateral sorting in a manner additive to Val660 (Reich et al 1996).…”