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Evolution of the opossum major histocompatibility complex: evidence for diverse alternative splice patterns and low polymorphism among class I genes
Author(s) -
Baker Michelle L.,
Melman Sandra D.,
Huntley James,
Miller Robert D.
Publication year - 2009
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1111/j.1365-2567.2008.02994.x
Subject(s) - biology , opossum , major histocompatibility complex , genetics , gene , mhc class i , monodelphis domestica , anatomy
Summary The opossum major histocompatibility complex (MHC) shares a similar organization with that of non‐mammals while containing a diverse set of class I genes more like that of eutherian (placental) mammals. There are 11 class I loci in the opossum MHC region, seven of which are known to be transcribed. The previously described Monodelphis domestica ( Modo ) ‐UA1 and Modo‐UG display characteristics consistent with their being classical and non‐classical class I genes, respectively. Here we describe the characteristics of the remaining five transcribed class I loci ( Modo‐UE , ‐UK , ‐UI , ‐UJ and ‐UM ). All five genes have peptide‐binding grooves with low or no polymorphism, contain unpaired cysteines with the potential to produce homodimer formation and display genomic organizational features that would be unusual for classical class I loci. In addition, Modo‐UJ and ‐UM were expressed in alternatively spliced mRNA forms, including a potentially soluble isoform of Modo‐UJ . Thus, the MHC region of the opossum contains a single class I gene that is clearly classical and six other class I genes each with its own unique characteristics that probably perform roles other than or in addition to antigen presentation.