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Updated: Sep 23, 2026

Using SecM Arrest Sequence as a Tool to Isolate Ribosome Bound Polypeptides
Published on: June 19, 2012
The primary structure and the disulfide links of the bovine relaxin-like factor (RLF)
Erika E Büllesbach1, Christian Schwabe
1Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, PO Box 250509, Charleston, South Carolina 29425, USA. bullesee@musc.edu
Abstract:
The relaxin-like factor (RLF), produced by the Leydig cells, is an essential link in the chain of events leading to the proper positioning of the testes during fetal development. The primary structure of RLF, as reported in the literature, is based solely upon cDNA sequences with chain lengths determined according to deduced processing sites and with relaxin-like cross-links. Biochemical characterization of bovine testicular RLF shows clearly that the endogenous hormone does consist of a 26 residue A chain and two forms of B chain, one containing 40 residues, the other 45. In addition, both B chains are 9 residues longer at the C terminus than the cDNA-deduced chain, and about 20% of the B chains have an additional 5 residue extension at the N terminus. Sequence analysis in combination with mass spectrometry and tryptic peptide mapping showed unambiguously that RLF is larger than previously assumed and that it has the relaxin-type disulfide bond distribution that makes it a bona fide member of the relaxin family of hormones.
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