Nucleotide, amino acid sequence and immunochemical characterization of the carboxy-terminal region of Sip1. (a) The nucleotide sequence containing 1,281 base-pairs of the cloned cDNA insertion was sequenced with an automated sequencer ABI Prism 310 Collection. The amino acid sequence predicted from the nucleotide sequence is 109 residues long. (Sip1 C-ter; GenBank accession number for Sip1 cDNA is AF030234) (b) The molecular size and the purity of the expressed protein was confirmed by 12% SDS-PAGE stained by Coomassie blue (lane 1) and the patients' serum immunoreactivity was analyzed by immunoblotting. Lane 2, the monoclonal antibody anti-histidine tail; lane 3, serum pool from the two patients with BD used in screening the library; lane 4, representative serum from a healthy subject; lane 5, control lane without serum. (c) Immunofluorescence analysis of Sip1 localization in EAhy-926 endothelial cells. The human IgG antibodies purified from patient's serum specific to Sip1 C-ter were used to analyse the cellular distribution of Sip1.