title: Localization of xenopsin and xenopsin precursor fragment immunoreactivities in the skin and gastrointestinal tract of Xenopus laevis.
abstract: Xenopsin (Xp) and xenopsin precursor fragment (XPF) are bioactive peptides derived from a single precursor molecule; both were isolated previously from extracts of Xenopus laevis skin. The present immunohistochemical study was undertaken to determine the specific cellular localization of these two peptides in the skin and also in the gastrointestinal tract of adult Xenopus. We report here that Xp-like and XPF-like immunoreactivities co-exist in the granular glands of the skin and specific granular cells in the lower esophagus and stomach. However, only Xp-like immunoreactivity, not XPF-like immunoreactivity, was detected in tall, thin cells of the duodenum and in club-shaped cells of the large intestine. The immunochemical co-localization of the two peptides in specific cells of the skin, lower esophagus and stomach suggests that the same gene is expressed in each of these cells, and that the precursor molecule undergoes similar post-translational processing. In contrast, the observation that certain cells of the duodenum and large intestine display only one peptide immunoreactivity suggests an alternative phenomenon, possibly involving selective peptide accumulation or expression of a different gene.
authors.affiliation: Department of Biological Sciences, Mount Holyoke College, South Hadley, MA 01075.
authors.forename: K C
authors.initials: KC
authors.lastname: Sadler
authors.forename: C L
authors.initials: CL
authors.lastname: Bevins
authors.forename: J C
authors.initials: JC
authors.lastname: Kaltenbach
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004064:Digestive System / Q000737:chemistry*; D005088:Exocrine Glands / Q000737:chemistry; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000032:analysis*; D009928:Organ Specificity; D010446:Peptide Fragments / Q000032:analysis; D010455:Peptides; D011498:Protein Precursors / Q000032:analysis*; D011499:Protein Processing, Post-Translational; D012867:Skin / Q000737:chemistry*; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000378:metabolism*
chemical_list: D009842:Oligopeptides; D010446:Peptide Fragments; D010455:Peptides; D011498:Protein Precursors; D029867:Xenopus Proteins; C016832:xenopsin