Evidence that the chromogranin B fragment 368-417 extracted from a pheochromocytoma is phosphorylated.

A rabbit antiserum was raised against a synthetic peptide corresponding to residues 403 to 417 of human chromogranin B. This peptide was chosen to match the potential C-terminal end of a putative proteolytic fragment of the protein located between dibasic doublets in positions 366-367 and in positions 418-419 of the precursor. A radioimmunoassay based on this antiserum was developed and used to detect the protein or a fragment thereof in a pheochromocytoma tumor extract.

Development of selective agonists and antagonists for the human vasoactive intestinal polypeptide VPAC(2) receptor.

Ro 25-1553 is a cyclic VIP derivative with a high affinity for the VPAC(2) receptor subtype. Our goal was to identify the modifications that support its selectivity for VPAC(2) receptors, and to develop a VIP or Ro 25-1553 analog behaving as a high affinity, VPAC(2) selective antagonist. The selectivity of Ro 25-1553 for the human receptor was supported mainly by the acetylation of the amino-terminus, by the introduction of a lysine residue in position 12, and by the carboxyl-terminal extension.

Evidence that the lizard helospectin peptides are O-glycosylated.

Six forms of helospectin (a vasoactive intestinal peptide analogue) were purified from the venom of the Heloderma horridum lizard. Their identification was performed by combining sequencing by automated Edman degradation and electrospray mass spectrometry analysis on the complete peptides and their tryptic fragments. The products resulting from the action of an O-glycosidase were also analysed.

Different vasoactive intestinal polypeptide receptor domains are involved in the selective recognition of two VPAC(2)-selective ligands.

A vasoactive intestinal polypeptide (VIP) analog, acylated on the amino-terminal histidine by hexanoic acid (C(6)-VIP), behaved as a VPAC(2) preferring agonist in binding and functional studies on human VIP receptors, and radioiodinated C(6)-VIP was a suitable ligand for binding studies on wild-type and chimeric receptors. We evaluated the properties of C(6)-VIP, its analog AcHis(1)-VIP, and the VPAC(2)-selective agonist Ro 25-1553 on the wild-type VPAC(1) and VPAC(2) receptors and on the chimeric receptors exchanging the different domains between both receptors. VIP had a normal affinity and efficacy on the chimeras starting with the amino-terminal VPAC(2) receptor sequence.