The Xenopus IP3 receptor: structure, function, and localization in oocytes and eggs.
To study the role of the IP3 receptor (IP3R) upon egg activation, cDNA clones encoding IP3R expressed in the Xenopus oocytes were isolated. By analyses of the primary structure and functional expression of the cDNA, Xenopus IP3R (XIP3R) was shown to have an IP3-binding domain and a putative Ca2+ channel region. Immunocytochemical studies revealed polarized distribution of XIP3R in the cytoplasm of the animal hemisphere in a well-organized endoplasmic reticulum-like structure and intensive localization in the perinuclear region of stage VI immature oocytes. In ovulated unfertilized eggs, XIP3R was densely enriched in the cortical region of both hemispheres in addition to its polarized localization. After fertilization, XIP3R showed a drastic change in its distribution in the cortical region. These results imply the predominant role of the XIP3R in both the formation and propagation of Ca2+ waves at fertilization.
Department of Molecular Neurobiology, University of Tokyo, Japan.
S
S
Kume
A
A
Muto
J
J
Aruga
T
T
Nakagawa
T
T
Michikawa
T
T
Furuichi
S
S
Nakade
H
H
Okano
K
K
Mikoshiba
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015220:Calcium Channels; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D005306:Fertilization; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007700:Kinetics; D008540:Meiosis / Q000187:drug effects; D051379:Mice; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D009865:Oocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D010063:Ovum / Q000166:cytology / Q000502:physiology*; D011374:Progesterone / Q000494:pharmacology; D011487:Protein Conformation; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D014982:Xenopus laevis
D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D009838:Oligodeoxyribonucleotides; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D011374:Progesterone; D015544:Inositol 1,4,5-Trisphosphate; D004247:DNA