cholera toxin is secreted
by the gram-negative bacterium Vibrio cholerae. It is a gastrointestinal
toxin that increases adenylate cyclase activity of mucosa
of the small intestine, thereby increasing cyclic AMP within
these cells. Cyclic AMP stimulates active transport of ions by
these epithelial cells, resulting in a large efflux of Na+ and water
into the gut. The toxin enters cells by interacting with a GM1
ganglioside on the cell surface. After entry, the A1 subunit catalyzes
the transfer of an ADP-ribose unit from NAD+ to an arginine
side chain of the adenylate cyclase regulatory G protein,
blocking its GTPase activity. Thus the adenylate cyclase deactivation
mechanism is destroyed, and cyclic AMP is continually
produced. The major sign of cholera poisoning is severe diarrhea;
several liters of body water may be lost within a few hours,
leading to shock and death if fluid is not replaced. Treatment
involves physiological support (including i.v. fluids) and antibiotics.
그림문자(GHS):
신호 어:
Danger
유해·위험 문구:
암호
유해·위험 문구
위험 등급
범주
신호 어
그림 문자
P- 코드
H332
흡입하면 유해함
급성 독성 물질 흡입
구분 4
경고
P261, P271, P304+P340, P312
H412
장기적 영향에 의해 수생생물에 유해함
수생 환경유해성 물질 - 만성
구분 3
P273, P501
예방조치문구:
P262
눈, 피부, 의복에 묻지 않도록 하시오.
P273
환경으로 배출하지 마시오.
P280
보호장갑/보호의/보안경/안면보호구를 착용하시오.
P301+P310
삼켰다면 즉시 의료기관(의사)의 진찰을 받으시오.
CHOLERA TOXIN C화학적 특성, 용도, 생산
용도
Cholera Toxin from Vibrio cholerae has been used as a positive control in cAMP (cyclic AMP) assay for enterotoxins. It has been added as a supplement in cell culture media of primary tumors and epithelial cells.
Biochem/physiol Actions
Toxin consisting of an A subunit (27 kDa) surrounded by five B subunits (approximately 12 kDa each), which attach the toxin to ganglioside GM1 on the cell surface. The A subunit catalyzes ADP-ribosylation of the α-subunit of the stimulatory G protein (Gαs), reducing GTPase activity and activating the α-subunit. This activation of Gαs leads to an increase in the activity of adenylyl cyclase, resulting in increased levels of cAMP. Also ADP-ribosylates transducin in the eye rod outer segments, inactivating its GTPase activity. Cholera toxin has also been reported to ADP-ribosylate tubulin. Shown to be a potent mucosal vaccine adjuvant, inducing T helper cell type 2 responses by inhibiting the production of interleukin-12.
