Cheng H, Bjerknes M, Chen H
Department of Anatomy and Cell Biology, University of Toronto, Ontario, Canada.
Anat Rec. 1996 Mar;244(3):327-43. doi: 10.1002/(SICI)1097-0185(199603)244:3<327::AID-AR5>3.0.CO;2-V.
A subtraction screen isolated CRP-ductin (CRP), a gene expressed in intestinal crypts.
DNA sequencing, in situ hybridization, immunostaining, Western and Northern blotting were used to characterize murine CRP.
CRP is restricted to the intestine and its associated glands. In the small intestine, CRP mRNA is expressed in crypt cells at all stages of differentiation from the stem cells to the terminally differentiating cells of the crypt top, but not in the mature cells of the villus. In the colon, CRP mRNA is most heavily expressed in the mid-crypt. Expression is also seen in the pancreas and pancreatic ducts, and in the epithelium lining larger hepatic ducts, but not in the liver parenchyma or stomach. CRP protein is localized to the lumenal aspect of crypt cells in the small intestine. In the colon, the protein is seen in the lumenal aspect of surface epithelial cells. CRP protein is similarly found in the lumenal aspect of epithelial cells lining the pancreatic duct system and the larger hepatic ducts. Two cDNA variants, CRP-alpha and CRP-beta, were cloned from mouse jejunal epithelium. Their 3'-sequence differs in an 82-bp domain unique to CRP-beta.
The CRP-alpha sequence predicts a protein with a short cytoplasmic region, a transmembrane domain, and a large extracellular region composed of many repeats (8 scavenger receptor domains, 5 CUB-domains, 1 ZP-domain, and 6 copies of a previously unreported domain which we call the CRP-domain). The structure of the CRP protein suggests a role in ligand interaction; possible functions are discussed.
通过消减筛选分离出CRP-ductin（CRP），这是一种在肠隐窝中表达的基因。
采用DNA测序、原位杂交、免疫染色、蛋白质免疫印迹和Northern印迹法对小鼠CRP进行特征分析。
CRP仅限于肠道及其相关腺体。在小肠中，CRP mRNA在从干细胞到隐窝顶部终末分化细胞的所有分化阶段的隐窝细胞中表达，但在绒毛的成熟细胞中不表达。在结肠中，CRP mRNA在隐窝中部表达最为强烈。在胰腺和胰管以及较大肝管的上皮中也有表达，但在肝实质或胃中没有表达。CRP蛋白定位于小肠隐窝细胞的腔面。在结肠中，该蛋白见于表面上皮细胞的腔面。在胰管系统和较大肝管的上皮细胞的腔面也同样发现了CRP蛋白。从小鼠空肠上皮中克隆出两种cDNA变体，CRP-α和CRP-β。它们的3'序列在CRP-β特有的一个82bp结构域中有所不同。
CRP-α序列预测的蛋白质具有短的胞质区域、一个跨膜结构域和一个由许多重复序列组成的大的细胞外区域（8个清道夫受体结构域、5个CUB结构域、1个ZP结构域以及6个我们称之为CRP结构域的先前未报道结构域的拷贝）。CRP蛋白的结构表明其在配体相互作用中发挥作用；并对可能的功能进行了讨论。
