Rabbit anti-Human SART3 polyclonal antibody

The expression of 18 149 genes have been analysed during the differentiation of the human intestinal cell line Caco-2. cDNA probes from undifferentiated and differentiated Caco-2 cells were separately hybridised to EST DNAs spotted in an array on a nylon membrane. A remarkable change in the transcriptome was observed during the differentiation of the Caco-2 cells. 8762 of the 18 149 genes analysed were expressed above background level in the undifferentiated Caco-2 cells, whereas only 5767 genes were expressed above background in differentiated Caco-2 cells. This pattern of expression was caused by a general down-regulation of genes in the low abundance class. Similar results were found using mouse small intestinal crypt and villus cells, suggesting that the phenomenon also occurs in the intestine in vivo. The expression data were subsequently used in a search for markers for subsets of epithelial cells by performing reverse transcriptase-polymerase chain reaction on RNA extracted from laser dissected intestinal crypt and villi. In a screen of eight transcript one - SART3 - was identified as a marker for human colonic crypts. (C) 2002 Elsevier Science B.V. All rights reserved.

Spliceosomal small nuclear ribonucleoprotein particles (snRNPs) are required for pre-mRNA splicing throughout the nucleoplasm, yet snRNPs also concentrate in Cajal bodies (CBs). To address a proposed role of CBs in snRNP assembly, we have used fluorescence resonance energy transfer (FRET) microscopy to investigate the subnuclear distribution of specific snRNP intermediates. Two distinct complexes containing the protein SART3 (p110), required for U4/U6 snRNP assembly, were localized: SART3 . U6 snRNP and SART3 . U4/U6 snRNP. These complexes segregated to different nuclear compartments, with SART3 . U6 snRNPs exclusively in the nucleoplasm and SART3 . U4/U6 snRNPs preferentially in CBs. Mutant cells lacking the CB-specific protein coilin and consequently lacking CBS exhibited increased nucleoplasmic levels of SART3 . U4/U6 snRNP complexes. Reconstitution of CBs in these cells by expression of exogenous coilin restored accumulation of SART3 . U4/U6 snRNP in CBs.Thus, while some U4/U6 snRNP assembly can occur in the nucleoplasm, these data provide evidence that SART3 . U6 snRNPs form in the nucleoplasm and translocate to CBS where U4/U6 snRNP assembly occurs.