Two forms of human Inscuteable-related protein that links Par3 to the Pins homologues LGN and AGS3

doi:10.1016/j.bbrc.2006.01.050

Biochemical and Biophysical Research Communications

Volume 341, Issue 4, 24 March 2006, Pages 1001-1006

https://doi.org/10.1016/j.bbrc.2006.01.050 Get rights and content

Abstract

In cell polarization of Drosophila neuroblasts, Inscuteable (Insc) functions via tethering Partner of Insc (Pins) to Bazooka, homologous to human cell polarity protein Par3. However, little has been known about mammalian homologues of Insc. Here we describe cloning of two distinct cDNAs from human Insc gene, which is differentially expressed from alternative first exons: one encodes 579 amino acids, whereas the other lacks the N-terminal 47 amino acids. In contrast to human homologues for Pins and Par3, human Insc exhibits a weak homology with the Drosophila counterpart. Nevertheless, human Insc proteins bind to the human Pins homologues LGN and AGS3, and also to human Par3 and its related protein Par3β. Although LGN by itself is incapable of interacting with Par3, coexpression of human Insc leads to the interaction between LGN and Par3, indicating that human Insc plays an evolutionarily conserved role as an adaptor protein that links Pins to Par3.

Section snippets

Materials and methods

Isolation of cDNAs for human Insc. A search of EST databases with a nucleotide region encoding amino acids 539–593 of Drosophila Insc yielded a human EST clone (BQ675721) that encodes amino acids 211–579 of a novel protein, and subsequently another human EST clone (BU147420) that contains amino acids 48–561 of the novel protein. Based on sequences of the EST clones, we synthesized the two unique oligonucleotide primers 5′-GCGGATCCAGTTTCCGGTGCTTGTACCC-3′ (forward primer) and 5′-GCGAATTCA

Primary structure of human Inscuteable

On the basis of sequences of EST clones exhibiting similarities to Drosophila Insc, we cloned cDNAs for human homologue of Insc (for detail, see Materials and methods). We obtained two distinct forms of the transcripts: one encodes 579 amino acids, tentatively designated the long form (GenBank Accession No. AB236159); and the other encodes the short form of 532 amino acids (GenBank Accession No. AB236158), which lacks the N-terminal 47 amino acids (Fig. 1A). In the C-terminal half, human Insc

Concluding remarks

In the present study, we have identified the two forms of the human Insc transcript: the Insc gene is differentially expressed from alternative first exons. The long form encodes 579 amino acids, whereas the short one lacks the N-terminal 47 amino acids (Fig. 1, Fig. 2); and tissue expression pattern of the long form is different from that of the short form (Fig. 3). Both forms of human Insc can interact with the human Pins homologues LGN and AGS3 (Fig. 4A), and with human Par3 and its related

Acknowledgments

We are grateful to Miki Matsuo (Kyushu University), Yohko Kage (Kyushu University and JST), Natsuko Yoshiura (Kyushu University), and Namiko Kubo (Kyushu University and JST) for technical assistance, and to Minako Nishino (Kyushu University and JST) for secretarial assistance. This work was supported in part by Grants-in-Aid for Scientific Research and National Project on Protein Structural and Functional Analyses from the Ministry of Education, Culture, Sports, Science and Technology of Japan,

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Citation Excerpt :
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^☆: Abbreviations: aPKC, atypical protein kinase C; Gα, the α subunit of trimeric G protein; Pins, Partner of Inscuteable; Insc, Inscuteable; PCR, polymerase chain reaction; 5′-RACE, 5′-rapid amplification of cDNA ends.

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Two forms of human Inscuteable-related protein that links Par3 to the Pins homologues LGN and AGS3☆

Abstract

Section snippets

Materials and methods

Primary structure of human Inscuteable

Concluding remarks

Acknowledgments

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