Differential processing of the neurotensin/neuromedin N precursor in the mouse.
Posttranslational processing of the neurotensin/neuromedin N (NT/NN) precursor has been investigated in mouse brain and small intestine by means of region-specific radioimmunoassays coupled to chromatographic fractionations. In brain, total NT/NN immunoreactivity measured with a common C-terminal antiserum was 15.72 pmol/g. NT measured with an N-terminal antiserum was 9.74 pmol/g and NN measured with an N-terminal antiserum was 5.98 pmol/g. In small intestine, combined NT/NN immunoreactivity was 108.55 pmol/g, consisting of 66.37 pmol/g NT but only 0.96 pmol/g NN. Gel permeation chromatography and reverse phase HPLC revealed that the large discrepancy in the NT and NN values obtained in small intestinal extracts was due to the presence of a high molecular weight, hydrophobic peptide, which was reactive only with the common C-terminally directed antiserum. Pepsinization of this generated an immunoreactive peptide with similar chromatographic characteristics to NN. In mouse intestine, NN is only partially cleaved from the common NT/NN precursor, resulting in the presence of an N-terminally extended molecular species. This novel molecular species of neuromedin N may be the physiological mediator of certain peripheral biological effects hitherto attributed to neurotensin or neuromedin N.
Shaw
C
C
Department of Medicine, Queen's University of Belfast, N. Ireland.
McKay
D
D
Johnston
C F
CF
Halton
D W
DW
Fairweather
I
I
Kitabgi
P
P
Buchanan
K D
KD
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D007421:Intestine, Small / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009496:Neurotensin / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011863:Radioimmunoassay; D014357:Trypsin
D010446:Peptide Fragments; D011498:Protein Precursors; C042090:neuromedin N; D009496:Neurotensin; D014357:Trypsin