Identification and characterization of a novel gastric peptide hormone: the motilin-related peptide.
OBJECTIVE
This study looked for new proteins with expression restricted to the gastric epithelium that may provide insight to the differentiation and function of the gastric unit.


METHODS
A novel complementary DNA was isolated and sequenced, and its expression was examined in mouse tissues at both messenger RNA and protein levels. Subcellular localization was studied using immunoelectron microscopy. The posttraductional processing of the protein was analyzed in vitro by protein microsequencing and in vivo by Western blotting.


RESULTS
We identified a novel protein that is mainly expressed by the secretory granules of the stomach enteroendocrine cells. This protein has sequence similarity with prepromotilin, the precursor of the motilin hormone and the motilin-associated peptide. As for the prepromotilin, a posttraductional maturation leads to a secreted peptide that is further cleaved at a dibasic site and gives rise to the motilin-related peptide (MTLRP) and MTLRP-associated peptide.


CONCLUSIONS
We have identified and characterized a novel gene encoding the preproMTLRP protein. MTLRP presents similarity to motilin and is specifically expressed by enteroendocrine cells of the stomach and therefore represents a novel hormone.
Tomasetto
C
C
Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS/INSERM Unité 184/ULP, Strasbourg, France.
Karam
S M
SM
Ribieras
S
S
Masson
R
R
Lefèbvre
O
O
Staub
A
A
Alexander
G
G
Chenard
M P
MP
Rio
M C
MC
D000818:Animals; D000906:Antibodies; D001483:Base Sequence; D015152:Blotting, Northern; D019556:COS Cells; D003001:Cloning, Molecular; D003594:Cytoplasmic Granules / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D004702:Endocrine Glands / Q000166:cytology; D020895:Enterocytes / Q000737:chemistry / Q000502:physiology; D005753:Gastric Mucosa / Q000737:chemistry* / Q000166:cytology; D015870:Gene Expression / Q000502:physiology; D054439:Ghrelin; D051379:Mice; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D009037:Motilin / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D036361:Peptide Hormones; D011498:Protein Precursors / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D011817:Rabbits; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic / Q000502:physiology
D000906:Antibodies; D054439:Ghrelin; D036361:Peptide Hormones; D011498:Protein Precursors; D012333:RNA, Messenger; C058325:prepromotilin; D009037:Motilin