Isolation and characterization of Xenopus laevis homologs of the mouse inv gene and functional analysis of the conserved calmodulin binding sites.
The homozygous inv (inversion of embryonic turning) mouse mutant shows situs inversus and polycystic kidney disease, both of which result from the lack of the inv gene. Previously, we suggested that inv may be important for the left-right axis formation, not only in mice but also in Xenopus, and that calmodulin regulates this inv protein function. Here, we isolated and characterized two Xenopus laevis homologs (Xinv-1 and Xinv-2) of the mouse inv gene, and performed functional analysis of the conserved IQ motifs that interact with calmodulin. Xinv-1 expresses early in development in the same manner as mouse inv does. Unexpectedly, a full-length Xenopus inv mRNA did not randomize cardiac orientation when injected into Xenopus embryos, which is different from mouse inv mRNA. Contrary to mouse inv mRNA, Xenopus inv mRNA with mutated IQ randomized cardiac orientation. The present study indicates that calmodulin binding sites (IQ motifs) are crucial in controlling the biological activity of both mouse and Xenopus inv proteins. Although mouse and Xenopus inv genes have a quite similar structure, the interaction with calmodulin and IQ motifs of Xenopus inv and mouse inv proteins may regulate their function in different ways.
Yasuhiko
Yukuto
Y
Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Shiokawa
Koichiro
K
Mochizuki
Toshio
T
Asashima
Makoto
M
Yokoyama
Takahiko
T
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D017089:Ankyrin Repeat; D019521:Body Patterning / Q000235:genetics; D002148:Calmodulin-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D018076:DNA, Complementary / Q000302:isolation & purification; D006321:Heart / Q000196:embryology; D051379:Mice; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary / Q000235:genetics; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics*; D014982:Xenopus laevis / Q000196:embryology / Q000235:genetics*
D002148:Calmodulin-Binding Proteins; D018076:DNA, Complementary; C491947:Invs protein, mouse; D014157:Transcription Factors