Small-intestinal dysfunction accompanies the complex endocrinopathy of human proprotein convertase 1 deficiency
J. Clin. Invest. Robert S. Jackson, et al. 112:1550 doi:10.1172/JCI18784 [Go to this article.]

Figure 3
Subjects A’s plasma contained products that normally result from PC1-mediated proglucagon processing. (a) PC1 in intestinal L cells cleaves proglucagon to glicentin, oxyntomodulin, and GLP-1 and -2, while in islet A cells PC2 forms glucagon, 9-kDa peptide, and major proglucagon fragment (MPGF). GRPP, glicentin-related pancreatic peptide; IP, intervening peptide. (b) Reverse-phase HPLC of postprandial plasma with RIA of eluted amidated C-terminal GLP-1 revealed the continued presence of mature GLP-1^7-36amide. ↓, GLP-1 standards. (c) GLP-2 also was detectable in postprandial plasma using size-exclusion gel chromatography and RIA of eluted mid-sequence GLP-2 (mid–GLP-2). (d) In response to food, Subject A’s apparently normal fasting plasma levels of glicentin, oxyntomodulin, and glucagon rose abnormally high. Size-exclusion gel chromatography with RIA (antiserum 4304) of eluted mid-sequence glucagon (present in glicentin, oxyntomodulin, and glucagon) was applied to plasma from Subject A (top) and five pooled controls (bottom) during fasting (left) and 1 hour after food intake (right). Oxyn., oxyntomodulin; K_diss, coefficient of distribution; ↓, standards; IR, immunoreactivity.