Fig 1
From: Convergence and Divergence of the Signaling Pathways for Insulin and Phosphoinositolglycans
Schema for the generation (A) and structure (B) of PIG-P.
PIG-P is derived from the carboxy-terminal protein portion and GPI anchor of Gcelp from Saccharomyces cerevisiae by enzymatic cleavages in vitro with V8 protease from Staphylococcus aureus and PI-specific PLC from Bacillus cereus. The glycan portion consists of nonacetylated glucosamine gly-cosidically linked to a series of three mannose residues from which (the distal one) an additional mannose side chain can branch off (typical for yeast). The cleavage sites within the peptide portion for pronase and within the PIG portion for de-phosphorylation of the two phosphodiester bridges by aqueous hydrogen fluoride (HF) or for deamination of the glucosamine residue by nitrous acid (NA) are indicated by arrows (A). The methods used for structural elucidation of special epitopes of the PIG-P are indicated (B) (24).