The reference OMIM entry for this protein is 603130

Attractin; atrn
Mahogany, mouse, homolog of; mgca

CLONING

Attractin is a human serum glycoprotein that is rapidly expressed on activated T cells and released extracellularly after 48 to 72 hours. Duke-Cohan et al. (1998) cloned attractin and found that, as in its natural serum form, it mediates the spreading of monocytes that becomes the focus for the clustering of nonproliferating T lymphocytes. There are 2 mRNA species with hematopoietic tissue-specific expression that code for a 134-kD protein with a putative serine protease catalytic serine, 4 EGF-like motifs, a CUB domain, a C-type lectin domain, and a domain homologous with the ligand-binding region of the common gamma cytokine chain. Except for the last 2 domains, the overall structure shares high homology with a protein of Caenorhabditis elegans, suggesting that attractin has evolved new domains and functions in parallel with the development of cell-mediated immunity. Gunn et al. (1999) and Nagle et al. (1999) independently and simultaneously cloned the mouse 'mahogany' gene. Using a positional cloning strategy, Gunn et al. (1999) identified a mahogany candidate gene, Mgca, on chromosome 2. The normal 9-kb Mgca mRNA is expressed in brain, skin, heart, kidney, liver, and lung. The sequence of the extracellular domain of Mgca protein is 93% identical to the sequence of attractin. The peptide sequence of attractin terminates 6 codons after it diverges from Mgca and 11 codons before the transmembrane domain of Mgca. Using a probe corresponding to the amino-terminal region of mouse Mgca, Gunn et al. (1999) detected 2 main RNA isoforms of 8.5 and 4 kb in human tissues. They postulated that the 8.5-kb transcript is likely to encode the transmembrane form of human attractin because it is also detected by a probe corresponding to the Mgca C terminus. Gunn et al. (1999) also detected a human brain cDNA clone with 97% identity to the C-terminal 452 residues of Mgca. The site at which the attractin and human brain cDNAs diverge corresponds to a splice junction in the Mgca genomic sequence. When attractin was identified as the product of the murine 'mahogany' gene with connections to control of pigmentation and energy metabolism, and the 'mahogany' product was identified and shown to be a transmembrane protein, the possibility of a human membrane attractin in addition to the secreted form was raised. Tang et al. (2000) described the complete genomic sequence of attractin, focusing in particular on the exons coding for the 3-prime region, and showed how both human membrane and secreted attractin arise as a result of alternate splicing of the same gene. They found that soluble attractin arises from transcription of 25 sequential exons on 20p13, where the 3-prime terminal exon contains sequence from a long interspersed nuclear element-1 (LINE-1) retrotransposon insertion that includes a stop codon and a polyadenylation signal. The mRNA isoform for membrane attraction splices over the LINE-1 exon and includes 5 exons encoding transmembrane and cytoplasmic domains with organization and coding potential almost identical to that of the mouse gene. The relative abundance of soluble and transmembrane isoforms measured by RT-PCR is differentially regulated in lymphoid tissues. Because activation of peripheral blood leukocytes with phytohemagglutinin induces strong expression of cell surface attractin followed by release of soluble attractin, these results suggested to Tang et al. (2000) that LINE-1 insertion, a genomic event unique to mamm ... More on the omim web site

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Oct. 19, 2018: Protein entry updated
Automatic update: OMIM entry 603130 was added.

Oct. 19, 2018: Additional information
Initial protein addition to the database. This entry was referenced in Bryk and co-workers. (2017).