PA1b, a plant peptide, induces intracellular [Ca^(2+)] in- crease via Ca^(2+) influx through the L-type Ca^(2+) channel and triggers secretion in pancreatic β cells  

作　　者：HU ZhiTao1, DUN XinPeng1, ZHANG Ming1, ZHU HongLiang1, XIE Li1, WU ZhengXing1, CHEN ZhengWang1 & XU Tao1,2 1 Joint Laboratory of Institute of Biophysics and Huazhong University of Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China 2 National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China. 

出　　处：《Science China(Life Sciences)》2007年第3期285-291,共7页中国科学（生命科学英文版）

基　　金：the National Natural Science Foundation of China (Grant Nos. 30370674,30470448, and 30470646);the CAS Project (Grant No. KSCX2-SW-224);the China "863" Program (Grant No. 2012AA214066);The laboratory of Tao Xu is also supported by the Partner Group Scheme of the Max Planck Institute for Bio-physical Chemistry, Gttingen

摘　　要：Using alginic acid to adsorb polypeptides at pH 2.7, we isolated a peptide pea albumin 1b (PA1b) from pea seeds. The PA1b is a single chain peptide consisting of 37 amino acid residues with 6 cysteines which constitutes the cystine-knot structure. Using microfluorometry and patch clamp techniques, we found that PA1b significantly elevated the intracellular calcium level ([Ca2+ ]i) and elicited membrane capacitance increase in the primary rat pancreatic β cells. The PA1b effect on [Ca2+]i elevation was abolished in the absence of extracellular Ca2+ or in the presence of L-type Ca2+ channel blocker, ni- modipine. Interestingly, we found that PA1b significantly depolarized membrane potential, which could lead to the opening of voltage-dependent L-type Ca2+ channels and influx of extracellular Ca2+, and then evoke robust secretion. In this study we identified the plant peptide PA1b which is capable of affecting the excitability and function of mammalian pancreatic β cell.Using alginic acid to adsorb polypeptides at pH 2.7, we isolated a peptide pea albumin 1b (PA1b) from pea seeds. The PA1b is a single chain peptide consisting of 37 amino acid residues with 6 cysteines which constitutes the cystine-knot structure. Using microfluorometry and patch clamp techniques, we found that PA1b significantly elevated the intracellular calcium level ([Ca2+ ]i) and elicited membrane capacitance increase in the primary rat pancreatic β cells. The PA1b effect on [Ca2+]i elevation was abolished in the absence of extracellular Ca2+ or in the presence of L-type Ca2+ channel blocker, ni- modipine. Interestingly, we found that PA1b significantly depolarized membrane potential, which could lead to the opening of voltage-dependent L-type Ca2+ channels and influx of extracellular Ca2+, and then evoke robust secretion. In this study we identified the plant peptide PA1b which is capable of affecting the excitability and function of mammalian pancreatic β cell.

关 键 词：channel and triggers secretion in pancreatic PA1b influx through the L-type Ca a plant peptide type 

分 类 号：Q946[生物学—植物学]