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On the origin of intestinal transferrin
K Schümann1, B Elsenhans, W Forth
1Walther Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Federal Republic of Germany.
Research in Experimental Medicine. Zeitschrift Fur Die Gesamte Experimentelle Medizin Einschliesslich Experimenteller Chirurgie
|January 1, 1988
Summary
This study investigated protein synthesis in rat jejunal segments and liver cells using 35S-L-methionine. Results indicate no transferrin synthesis in the jejunum, despite its presence and correlation with plasma levels.
Area of Science:
- Biochemistry
- Physiology
Background:
- Protein synthesis is crucial for cellular function.
- Transferrin plays a vital role in iron transport.
- Investigating tissue-specific protein synthesis aids understanding of physiological processes.
Purpose of the Study:
- To measure and compare protein synthesis rates in rat jejunal segments and liver cells.
- To determine if the jejunal mucosa synthesizes transferrin.
- To assess the relationship between jejunal and plasma transferrin.
Main Methods:
- Utilized 35S-L-methionine incorporation into TCA-precipitable protein to quantify synthesis.
- Employed immunoelectrophoresis and autoradiography for semiquantitative analysis of specific proteins (transferrin, IgG).
- Compared transferrin in plasma, bile, and intestinal mucosa using immunoblots after isoelectric focusing.
Main Results:
- No detectable transferrin synthesis was observed in the jejunal mucosa.
- 35S-L-methionine incorporation into TCA precipitates and IgG continued in jejunal segments for over 2 hours.
- A strong positive correlation (r=0.88) was found between mucosal and plasma transferrin levels in normal and iron-deficient rats.
- Immunological cross-reactivity and identical isoelectric focusing patterns confirmed similarity between plasma and mucosal transferrin.
Conclusions:
- The jejunal mucosa does not appear to synthesize transferrin.
- Jejunal transferrin likely originates from plasma, with its presence correlating to plasma levels.
- The methodology is sensitive enough to detect low levels of transferrin synthesis.