Novel cysteine-rich secretory protein in the buccal gland secretion of the parasitic lamprey, Lethenteron japonicum.
Lampreys are one of the most primitive vertebrates diverged some 500 million years ago. It has long been known that parasitic lampreys secrete anticoagulant from their buccal glands and prevent blood coagulation of host fishes. We found two major protein components of 160 and 26 kDa in the buccal gland secretion of parasitic river lamprey, Lethenteron japonicum. The larger protein was identified as river lamprey plasma albumin. The complete primary structure of the 26-kDa protein was determined by protein and cDNA analysis. It belonged to the cysteine-rich secretory protein (CRISP) superfamily that includes recently identified reptile venom ion-channel blockers. Lamprey CRISP blocked depolarization-induced contraction of rat-tail arterial smooth muscle, but showed no effect on caffeine-induced contraction. The result suggests that lamprey CRISP is an L-type Ca(2+)-channel blocker and may act as a vasodilator, which facilitates the parasite to feed on the host's blood. The lamprey CRISP protein contains a number of short insertions throughout the sequence, when aligned with reptilian venom CRISP proteins, probably due to the large evolutionary distance between the Agnatha and the Reptilia, and may represent a novel class of venom CRISP family proteins.
Ito
Naoko
N
Life Science Course, Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan.
Mita
Mitsuo
M
Takahashi
Yoshiaki
Y
Matsushima
Ayano
A
Watanabe
Yuichi G
YG
Hirano
Shigeki
S
Odani
Shoji
S
D000418:Albumins / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000502:physiology; D001483:Base Sequence; D002121:Calcium Channel Blockers / Q000737:chemistry / Q000494:pharmacology; D003001:Cloning, Molecular; D003545:Cysteine / Q000737:chemistry*; D005088:Exocrine Glands / Q000378:metabolism; D066298:In Vitro Techniques; D007798:Lampreys / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000494:pharmacology; D008969:Molecular Sequence Data; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D051381:Rats; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013623:Tail / Q000098:blood supply
D000418:Albumins; D002121:Calcium Channel Blockers; D008562:Membrane Glycoproteins; D003545:Cysteine