LRRC23 explained

Leucine-rich repeat-containing protein 23 is a protein that in humans is encoded by the LRRC23 gene.^{[1] [2] [3]}

Function

The function of LRRC23 is unknown. It is a member of the leucine-rich repeat family of proteins, which are known for participating in protein-protein interactions. Experimental evidence suggests that LRRC23 interacts with the CD28 protein in a pathway related to the immune system and development of regulatory T cells that control spontaneous autoimmune disease.^[4]

Protein sequence

LRRC23 spans 343 residues containing two varieties of internally repeating sequence. Detected and aligned by RADAR,^[5] the most abundant repeat is the leucine-rich repeat, repeating 9 times in bases 89-287. The other repeated sequence occurs twice in bases 3-36. The RADAR program output, below, summarizes the composition and location of all the repeats and aligns them for comparison against each other.

The human genome produces three known variants of LRRC23.^[3] The largest splice variant, variant 3, contains 8 exons. Variants 1 and 2 use alternative first exons, and variant 2 excludes the seventh exon, giving it a total of seven exons making up the mRNA.

Protein structure

Although the actual structure of LRRC23 is unknown, comparison to the crystal structures of various similar proteins such as 2OMW A (e-value 1.00e-17) reveals a structure typical of other leucine-rich repeat proteins. Alternating beta sheets and coils create a spiraled peptide chain forming an arch shape with beta-sheets occupying the concave surface.^[6]

The aligned structure of 2OMW_A with LRRC23 spans acids 72-272 of the LRRC23 protein. Conserved asparagines are highlighted in yellow, showing the regularity of spacing and repeat structure within. This model was generated using Cn3D software provided by NCBI.

Further reading

• Maruyama K, Sugano S . Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides . Gene . 138 . 1–2 . 171–4 . Jan 1994 . 8125298 . 10.1016/0378-1119(94)90802-8 .
• Ansari-Lari MA, Muzny DM, Lu J, Lu F, Lilley CE, Spanos S, Malley T, Gibbs RA . A gene-rich cluster between the CD4 and triosephosphate isomerase genes at human chromosome 12p13 . Genome Research . 6 . 4 . 314–26 . Apr 1996 . 8723724 . 10.1101/gr.6.4.314 . free .
• Bonaldo MF, Lennon G, Soares MB . Normalization and subtraction: two approaches to facilitate gene discovery . Genome Research . 6 . 9 . 791–806 . Sep 1996 . 8889548 . 10.1101/gr.6.9.791 . free .
• Ansari-Lari MA, Shen Y, Muzny DM, Lee W, Gibbs RA . Large-scale sequencing in human chromosome 12p13: experimental and computational gene structure determination . Genome Research . 7 . 3 . 268–80 . Mar 1997 . 9074930 . 10.1101/gr.7.3.268 . free .
• Suzuki Y, Yoshitomo-Nakagawa K, Maruyama K, Suyama A, Sugano S . Construction and characterization of a full length-enriched and a 5'-end-enriched cDNA library . Gene . 200 . 1–2 . 149–56 . Oct 1997 . 9373149 . 10.1016/S0378-1119(97)00411-3 .
• Tasheva ES, An K, Boyle DL, Conrad GW . Expression and localization of leucine-rich B7 protein in human ocular tissues . Molecular Vision . 11 . 452–60 . 2006 . 16030496 .

Notes and References

1. Tzachanis D, Berezovskaya A, Nadler LM, Boussiotis VA . Blockade of B7/CD28 in mixed lymphocyte reaction cultures results in the generation of alternatively activated macrophages, which suppress T-cell responses . Blood . 99 . 4 . 1465–73 . Feb 2002 . 11830501 . 10.1182/blood.V99.4.1465 . free .
2. Book: Chang TT, Kuchroo VK, Sharpe AH . Role of the B7-CD28/CTLA-4 pathway in autoimmune disease . 5 . 113–30 . Feb 2002 . 11826754 . 10.1159/000060550 . 3-8055-7308-1 . Current Directions in Autoimmunity . Signal Transduction Pathways in Autoimmunity .
3. Web site: Entrez Gene: LRRC23 leucine rich repeat containing 23.
4. Salomon B, Lenschow DJ, Rhee L, Ashourian N, Singh B, Sharpe A, Bluestone JA . B7/CD28 costimulation is essential for the homeostasis of the CD4+CD25+ immunoregulatory T cells that control autoimmune diabetes . Immunity . 12 . 4 . 431–40 . Apr 2000 . 10795741 . 10.1016/S1074-7613(00)80195-8 . free .
5. RADAR: European Molecular Biology Laboratory - European Bioinformatics Institute (EMBLE-EBI) Radar program: http://www.ebi.ac.uk/Tools/es/cgi-bin/jobresults.cgi/radar/radar-20100506-0807327109.html#
6. NCBI Structure CBlast https://www.ncbi.nlm.nih.gov/Structure/cblast/cblast.cgi?client=entrez&query_gi=206725447&hit=149242643&hsp=1&output=html&pagenum=1&epp=20&sort=evalue&view=graphic&subset=allmmdb