Garg R R, Bally-Cuif L, Lee S E, Gong Z, Ni X, Hew C L, Peng C
Department of Biology, York University, Toronto, ON, Canada.
Mol Cell Endocrinol. 1999 Jul 20;153(1-2):169-81. doi: 10.1016/s0303-7207(99)00044-1.
A full-length cDNA encoding for activin type IIB receptor (ActRIIB) was cloned from zebrafish embryos. It encodes a protein with 509 amino acids consisting of a signal peptide, an extracellular ligand binding domain, a single transmembrane region, and an intracellular kinase domain with predicted serine/threonine specificity. The extracellular domain shows 74-91% sequence identity to human, bovine, mouse, rat, chicken, Xenopus and goldfish activin type IIB receptors, while the transmembrane region and the kinase domain show 67-78% and 82-88% identity to these known activin IIB receptors, respectively. In adult zebrafish, ActRIIB mRNA was detected by RT-PCR in the gonads, as well as in non-reproductive tissues, including the brain, heart and muscle. In situ hybridization on ovarian sections further localized ActRIIB mRNA to cytoplasm of oocytes at different stages of development. Using whole-mount in situ hybridization, ActRIIB mRNA was found to be expressed at all stages of embryogenesis examined, including the sphere, shield, tail bud, and 6-7 somite. These results provide the first evidence that ActRIIB mRNA is widely distributed in fish embryonic and adult tissues. Cloning of zebrafish ActRIIB demonstrates that this receptor is highly conserved during vertebrate evolution and provides a basis for further studies on the role of activin in reproduction and development in lower vertebrates.
从斑马鱼胚胎中克隆出了编码激活素IIB型受体（ActRIIB）的全长cDNA。它编码一种含有509个氨基酸的蛋白质，该蛋白质由一个信号肽、一个细胞外配体结合结构域、一个单一跨膜区域和一个预测具有丝氨酸/苏氨酸特异性的细胞内激酶结构域组成。细胞外结构域与人类、牛、小鼠、大鼠、鸡、非洲爪蟾和金鱼的激活素IIB型受体的序列同一性为74%-91%，而跨膜区域和激酶结构域与这些已知的激活素IIB型受体的同一性分别为67%-78%和82%-88%。在成年斑马鱼中，通过RT-PCR在性腺以及包括脑、心脏和肌肉在内的非生殖组织中检测到了ActRIIB mRNA。卵巢切片的原位杂交进一步将ActRIIB mRNA定位到不同发育阶段卵母细胞的细胞质中。使用整胚原位杂交，发现在所检测的胚胎发育的各个阶段，包括囊胚期、盾胚期、尾芽期和6-7体节期，ActRIIB mRNA均有表达。这些结果首次证明ActRIIB mRNA广泛分布于鱼类胚胎和成年组织中。斑马鱼ActRIIB的克隆表明该受体在脊椎动物进化过程中高度保守，并为进一步研究激活素在低等脊椎动物生殖和发育中的作用提供了基础。
