Morn repeat containing 1

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RefSeq (mRNA)



RefSeq (protein)



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MORN1 containing repeat 1, also known as Morn1, is a protein that in humans is encoded by the MORN1 gene.[1][2]

The function of Morn1 is not yet well understood. Orthologs have been found in eukaryotes and bacteria.


The MORN1 gene is located on Chromosome 1 at locus 1p36.33 and contains 7 MORN repeats. It has 1641 base pairs in 14 exons in the reference sequence mRNA transcript.[3]

MORN1 is nearby the SKI gene which encodes the SKI protein, LOC100129534, and RER1 gene on the positive strand of chromosome 1.On the minus strand, the PEX10 gene occurs further upstream of Morn1.

Alternative splicing

MORN1 contains 19 different GT-AG introns, and 15 different mRNAs; 11 of which are produced by alternative splicing and 4 of which are unspliced. Of these variants there are 4 probable alternative promoters, 9 non-overlapping alternative last exons and 6 alternative polyadenylation sites. 753 bps of this gene are antisense (on + strand) to spliced SKI gene, and 193 bps to RER1[4] which may contribute to regulation of expression of itself or of its flanking genes.


File:MORN repeats.png
There are 7 consecutive MORN repeats in the Morn1 protein

The MORN1 gene encodes a protein of 497 amino acids and contains two overlapping conserved protein domains. The first is the MORN repeat region in which the protein contains 7 MORN repeats (at residues 38-211) belonging to protein family: pfam02493. The second is a multidomain uncharacterized protein conserved in bacteria: COG4642 which contains the MORN repeat region plus the beginning target sequence (1–211).[5] The other 286 amino acids are less conserved among orthologs (especially distant orthologs) and belong to no known protein family.

The unmodified protein is predicted to have a molecular weight of 53,835.05 Daltons and an isoelectric point of 6.673. The protein has no long hydrophobic regions, suggesting it is not a transmembrane protein.[6] It has been predicted to be localized in the cytoplasm, the nucleus or mitochondrial.[7]

The genomic context may not necessarily infer function, but Morn1 has been predicted to contain a second peroxisomal targeting signal using PSORTII at residues 451: RLPPAFKHL,[7] which may suggest interaction with PEX10 (see genomic context above).

Morn1 was also predicted to contain a nuclear export signal near the end of the protein at amino-acids LELH 334–338 (non-MORN repeat-containing region).[8]

Predicted Phosphorylation (Pho)and Glycosylation(Glc) sites
Listed top to bottom: Horse, Human, Mouse, Rat and Sea Urchin

Post-translational modification

Morn1 was predicted to have several glycosylation sites at the Serine 488 and at Threonine residues.[9] There were also conserved Serine, Tyrosine and Threonine residues that were predicted Phosphorylation sites that were conserved among orthologs.[10] See image of the Multiple Sequence alignment and Texshade.[11][12]


The Membrane Occupation and Recognition Nexus is a repeat is found in multiple copies in several proteins including junctophilins.[5] A MORN-repeat protein has been identified in the parasite Toxoplasma gondii and other Apicomplexan protists.[13]

In T. gondii, MORN1 plays role in nuclear division and daughter cell budding. It is specifically associated with the spindle poles, the anterior and interior rings of the inner membrane complex during asexual reproduction/sexual reproduction; budding; and schizogony (see Apicomplexan cellular morphology).

Over-expression of MORN1 resulted in specific, severe defects in nuclear segregation and daughter cell formation. It was hypothesized that “Morn1 functions as a linker protein between certain membrane regions and the parasite's cytoskeleton.”[14] The Morn repeats are not identical, but follow a general pattern of beginning with a YeG seqeuence, and specifically the subsequent Glycine residues are well conserved even within microbial orthologs which may suggest that the glycine residues may be important and/or involved in some structural function of the protein.

Tissue distribution

Expressed Sequence Tag and microarray data suggests that Morn1 is expressed predominantly in the brain, eyes, lungs, parathyroid, salivary gland, testis, kidneys, trachea, and to a lesser extent the ovaries, prostate, thymus and the trachea. It is expressed in adults and in fetuses. By health state, Morn1 appears to be expressed in the normal state, as well as germ cell and kidney tumors.[15]


The orthologs of the Morn1 protein are listed below obtained by BLAST[16] analysis. The conservation of this protein is conserved in mammals and invertebrates. Reptiles, insects and birds do not seem to show much conservation of this protein while bacteria and protists show similar conservation as in birds and reptiles, but these organisms are much more evolutionarily distant from humans.

Organism Accession Number % Identity to Human Gene
Equus caballus XP_001495156[17] 74
Mus musculus NP_001074569[18] 69
Canis familiaris XP_849172[19] 69
Rattus norvegicus NP_001005544[20] 66
Branchiostoma floridae (Lancelet) XP_002590560.1[21] 58
Strongylocentrotus purpuratus XP_793509.1[22] 58
Trichoplax adhaerens XP_002113780.1[23] 50
Chlamydomonas reinhardtii XP_001699198.1[24] 45
Xenopus Laevis (African clawed frog) NP_001088789[25] 41
Toxoplasma gondii XP_002364290[26] 36
Taeniopygia guttata XP_002192069[27] 35
Gallus gallus XP_416745[28] 33
Drosophila virilis XP_002048955.1[29] 29
Caenorhabditis elegans NP_492193.2[30] 22

Structure similarity

The red molecules are identical residues with Morn1, the Yellow are conserved molecules within a MORN repeat and the blue and gray molecules are those with little to no similarity.

Based on C-blast results[31] Morn1 has a sequence similarity to that of Chain A, of Histone methyltransferase Set79. Morn1 aligns with 77 amino acids of this chain from residues 81–158.


  1. "Entrez Gene: MORN repeat containing 1".
  2. Strausberg RL, Feingold EA, Grouse LH, et al. (December 2002). "Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences". Proc. Natl. Acad. Sci. U.S.A. 99 (26): 16899–903. Bibcode:2002PNAS...9916899M. doi:10.1073/pnas.242603899. PMC 139241. PMID 12477932.
  3. "NCBI GenBank Record: MORN repeat containing 1". 2014-03-22.
  4. "National Center for Biotechnology Information AceView".
  5. 5.0 5.1 "Conserved Domains: Conserved domains on MORN repeat-containing protein 1".
  6. Brendel V, Bucher P, Nourbakhsh IR, Blaisdell BE, Karlin S (March 1992). "Methods and algorithms for statistical analysis of protein sequences". Proc. Natl. Acad. Sci. U.S.A. 89 (6): 2002–6. Bibcode:1992PNAS...89.2002B. doi:10.1073/pnas.89.6.2002. PMC 48584. PMID 1549558.; "ISREC SAPS server".
  7. 7.0 7.1 "PSORT II: Prediction of Protein Sorting Signals and Localization Sites in Amino Acid Sequences".
  8. la Cour T, Kiemer L, Mølgaard A, Gupta R, Skriver K, Brunak S (June 2004). "Analysis and prediction of leucine-rich nuclear export signals". Protein Eng. Des. Sel. 17 (6): 527–36. doi:10.1093/protein/gzh062. PMID 15314210.
  9. "ExPasy: YinOYang (Prediction of glycosylation sites in proteomes: from post-translational modifications to protein function. R Gupta.Ph.D. thesis at CBS, 2001".
  10. "NetPHOS: Blom, N., Gammeltoft, S., and Brunak, S. "Sequence- and structure-based prediction of eukaryotic protein phosphorylation sites." Journal of Molecular Biology: 294(5): 1351–1362, 1999".
  11. "CLUSTAL W: Julie D. Thompson, Desmond G. Higgins and Toby J. Gibson".
  12. "TeXshade version 1.4, by Eric Beitz".
  13. Ferguson DJ, Sahoo N, Pinches RA, Bumstead JM, Tomley FM, Gubbels MJ (April 2008). "MORN1 has a conserved role in asexual and sexual development across the apicomplexa". Eukaryotic Cell. 7 (4): 698–711. doi:10.1128/EC.00021-08. PMC 2292627. PMID 18310354.
  14. Gubbels MJ, Vaishnava S, Boot N, Dubremetz JF, Striepen B (June 2006). "A MORN-repeat protein is a dynamic component of the Toxoplasma gondii cell division apparatus". J. Cell Sci. 119 (Pt 11): 2236–45. doi:10.1242/jcs.02949. PMID 16684814.
  15. "Genecards: Expression Data Morn1".
  16. "NCBI BLAST".
  17. "PREDICTED: MORN repeat-containing protein 1 [Equus caballus] - Protein - NCBI".
  18. "MORN repeat-containing protein 1 isoform 1 [Mus musculus] - Protein - NCBI".
  19. "PREDICTED: Similar to testis specific gene A2 [Canis familiaris] - Protein - NCBI".
  20. "MORN repeat-containing protein 1 [Rattus norvegicus] - Protein - NCBI".
  21. "Hypothetical protein BRAFLDRAFT_124536 [Branchiostoma floridae] - Protein - NCBI".
  22. "PREDICTED: MORN repeat-containing protein 1 isoform X4 [Strongylocentr - Protein - NCBI".
  23. "Hypothetical protein TRIADDRAFT_27169, partial [Trichoplax adhaerens] - Protein - NCBI".
  24. "Predicted protein, partial [Chlamydomonas reinhardtii] - Protein - NCBI".
  25. "Radial spoke head component 1 L homeolog [Xenopus laevis] - Protein - NCBI".
  26. "Membrane occupation and recognition nexus protein MORN1 [Toxoplasma go - Protein - NCBI".
  27. "PREDICTED: Hypothetical protein [Taeniopygia guttata] - Protein - NCBI".
  28. "Radial spoke head 1 homolog [Gallus gallus] - Protein - NCBI".
  30. "JunctoPHilin [Caenorhabditis elegans] - Protein - NCBI".
  31. "NCBI: Cblast".

Further reading