title: Characterization of a cellular retinol-binding protein from lamprey, Lethenteron japonicum.
abstract: Lampreys are ancestral representatives of vertebrates known as jawless fish. The Japanese lamprey, Lethenteron japonicum, is a parasitic member of the lampreys known to store large amounts of vitamin A within its body. How this storage is achieved, however, is wholly unknown. Within the body, the absorption, transfer and metabolism of vitamin A are regulated by a family of proteins called retinoid-binding proteins. Here we have cloned a cDNA for cellular retinol-binding protein (CRBP) from the Japanese lamprey, and phylogenetic analysis suggests that lamprey CRBP is an ancestor of both CRBP I and II. The lamprey CRBP protein was expressed in bacteria and purified. Binding of the lamprey CRBP to retinol (Kd of 13.2 nM) was identified by fluorimetric titration. However, results obtained with the protein fluorescence quenching technique indicated that lamprey CRBP does not bind to retinal. Northern blot analysis showed that lamprey CRBP mRNA was ubiquitously expressed, although expression was most abundant in the intestine. Together, these results suggest that lamprey CRBP has an important role in absorbing vitamin A from the blood of host animals.
authors.affiliation: Department of Cell Biology and Morphology, Akita University Graduate School of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan. mezaki@gipc.akita-u.ac.jp
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Mezaki
authors.forename: Mayako
authors.initials: M
authors.lastname: Morii
authors.forename: Kiwamu
authors.initials: K
authors.lastname: Yoshikawa
authors.forename: Noriko
authors.initials: N
authors.lastname: Yamaguchi
authors.forename: Mitsutaka
authors.initials: M
authors.lastname: Miura
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Imai
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Yoshino
authors.forename: Haruki
authors.initials: H
authors.lastname: Senoo
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D004926:Escherichia coli / Q000378:metabolism; D005786:Gene Expression Regulation; D007798:Lampreys / Q000235:genetics*; D008099:Liver / Q000378:metabolism; D010802:Phylogeny; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D054840:Retinol-Binding Proteins, Cellular / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D014018:Tissue Distribution / Q000235:genetics; D017186:Titrimetry; D014801:Vitamin A
chemical_list: D012333:RNA, Messenger; D054840:Retinol-Binding Proteins, Cellular; D014801:Vitamin A