Myotrophin (MTPN)
The protein contains 118 amino acids for an estimated molecular weight of 12895 Da.
Promotes dimerization of NF-kappa-B subunits and regulates NF-kappa-B transcription factor activity (By similarity). Plays a role in the regulation of the growth of actin filaments. Inhibits the activity of the F-actin-capping protein complex formed by the CAPZA1 and CAPZB heterodimer. Promotes growth of cardiomyocytes, but not cardiomyocyte proliferation. Promotes cardiac muscle hypertrophy. (updated: Jan. 7, 2015)
Protein identification was indicated in the following studies:
- Goodman and co-workers. (2013) The proteomics and interactomics of human erythrocytes. Exp Biol Med (Maywood) 238(5), 509-518.
- Lange and co-workers. (2014) Annotating N termini for the human proteome project: N termini and Nα-acetylation status differentiate stable cleaved protein species from degradation remnants in the human erythrocyte proteome. J Proteome Res. 13(4), 2028-2044.
- Hegedűs and co-workers. (2015) Inconsistencies in the red blood cell membrane proteome analysis: generation of a database for research and diagnostic applications. Database (Oxford) 1-8.
- Bryk and co-workers. (2017) Quantitative Analysis of Human Red Blood Cell Proteome. J Proteome Res. 16(8), 2752-2761.
- D'Alessandro and co-workers. (2017) Red blood cell proteomics update: is there more to discover? Blood Transfus. 15(2), 182-187.
Methods
The following articles were analysed to gather the proteome content of erythrocytes.
The gene or protein list provided in the studies were processed using the ID mapping API of Uniprot in September 2018. The number of proteins identified and mapped without ambiguity in these studies is indicated below.
Only Swiss-Prot entries (reviewed) were considered for protein evidence assignation.
| Publication | Identification 1 | Uniprot mapping 2 | Not mapped / Obsolete | TrEMBL | Swiss-Prot |
|---|---|---|---|---|---|
| Goodman (2013) | 2289 (gene list) | 2278 | 53 | 20599 | 2269 |
| Lange (2014) | 1234 | 1234 | 7 | 28 | 1224 |
| Hegedus (2015) | 2638 | 2622 | 0 | 235 | 2387 |
| Wilson (2016) | 1658 | 1528 | 170 | 291 | 1068 |
| d'Alessandro (2017) | 1826 | 1817 | 2 | 0 | 1815 |
| Bryk (2017) | 2090 | 2060 | 10 | 108 | 1942 |
| Chu (2018) | 1853 | 1804 | 55 | 362 | 1387 |
1 as available in the article and/or in supplementary material
2 uniprot mapping returns all protein isoforms as one entry
The compilation of older studies can be retrieved from the Red Blood Cell Collection database.
The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.
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Biological Process
Catecholamine metabolic process
Cell growth
Cellular response to mechanical stimulus
Cerebellar granule cell differentiation
Neuron differentiation
Positive regulation of cardiac muscle hypertrophy
Positive regulation of cell growth
Positive regulation of macromolecule biosynthetic process
Positive regulation of NF-kappaB transcription factor activity
Positive regulation of protein metabolic process
Regulation of barbed-end actin filament capping
Regulation of cell size
Regulation of striated muscle tissue development
Regulation of translation
Skeletal muscle tissue regeneration
Striated muscle cell differentiation
The reference OMIM entry for this protein is 606484
Myotrophin; mtpn
V-1
CLONING
Myotrophin, a 12-kD protein, was originally isolated by Sen et al. (1990) from the hypertrophied ventricles of spontaneously hypertensive rats and later by Sil et al. (1993) from dilated cardiomyopathic human hearts. Mukherjee et al. (1993) found that myotrophin increases the transcript levels of protooncogenes as well as the transcript levels of beta-myosin heavy chain (160760) and ANF (108780), markers for cardiac hypertrophy. Taoka et al. (1992) characterized Mtpn purified from rat cerebellum. The 117-amino acid protein contained an acetylated N terminus and 2.5 internal 33-amino acid ankyrin repeats. Sivasubramanian et al. (1996) identified a second half-ankyrin repeat in rat Mtpn. Northern blot analysis detected up to 7 transcripts between 0.4 and 4.3 kb expressed in all rat tissues examined. Highest levels were detected in brain, and lowest levels in skeletal muscle. By 3-dimensional alignment, Knuefermann et al. (2002) determined that mammalian myotrophin resembles a truncated I-kappa-B-alpha (NFKBIA; 164008) without the signal response domain and PEST sequence. See 611050 for information on MPD6, a tumor antigen encoded by a cryptic ORF in the 3-prime UTR of MTPN mRNA.GENE FUNCTION
By gel shift assays, Sivasubramanian et al. (1996) determined that recombinant rat myotrophin interacted with p50 NFKB1 (164011)-p65 RELA (164014) complexes and formed a ternary protein-DNA complex. Myotrophin antibodies inhibited formation of the complexes, and p50 and p65 antibodies supershifted the complexes. Knuefermann et al. (2002) determined that endogenous HeLa cell MTPN is predominantly cytoplasmic and translocates to the nucleus during sustained NFKB activation. They presented evidence that recombinant mammalian myotrophin can promote the formation of transcriptionally repressive p50-p50 homodimers from monomeric p50 proteins and can convert the preformed active p50-p65 heterodimers to the p50-p50 and p65-p65 homodimers. Overexpression of myotrophin significantly repressed NFKB-driven transcription of a reporter plasmid. Hiwatashi et al. (2002) found that, in rat adrenal glands, Mtpn was more highly expressed in noradrenergic chromaffin cells than in adrenergic chromaffin cells that preferentially express the glucocorticoid receptor 138040. In cultured bovine adrenal medullary cells, a synthetic glucocorticoid inhibited expression of Mtpn, and the inhibition was reversed by a glucocorticoid receptor antagonist. Yamakuni et al. (2002) found that transfected rat pheochromocytoma cells overexpressing rat Mtpn showed enhanced K+-induced dopamine secretion that was associated with elevated intracellular Ca(2+) levels and increased dense-cored vesicle number. Poy et al. (2004) showed that Mtpn is a target of the microRNA miR375 (611173). Inhibition of Mtpn by small interfering (si) RNA mimicked the effects of miR375 on glucose-stimulated insulin secretion and exocytosis, in which overexpression of miR375 suppressed glucose-induced insulin secretion and inhibition of endogenous miR375 function enhanced insulin secretion. Repression of Mtpn was mediated by a single miRNA375 target site in the 3-prime untranslated region of the Mtpn gene.MAPPING
By fluorescence in situ hybridization, Mitra et al. (2001) mapped the MTPN gene to chromosome 7q33-q35. ... More on the omim web site
Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated
Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated
Nov. 23, 2017: Protein entry updated
Automatic update: Uniprot description updated
March 16, 2016: Protein entry updated
Automatic update: OMIM entry 606484 was added.