Stoichiometry of HLA Class II-Invariant Chain Oligomers

BACKGROUND: The HLA gene complex encodes three class II isotypes, DR, DQ, and DP. HLA class II molecules are peptide receptors that present antigens for recognition by T lymphocytes. In antigen presenting cells, the assembly of matched α and β subunits to heterodimers is chaperoned by invariant chain (Ii). Ii forms a homotrimer with three binding sites for class II heterodimers. The current model of class II and Ii structure states that three αβ heterodimers bind to an Ii trimer. METHODOLOGY/PRINCIPAL FINDINGS: [corrected] We have now analyzed the composition and size of the complexes of class II and Ii using epitope tagged class II subunits and density gradient experiments. We show here that class II-Ii oligomers consist of one class II heterodimer associated with one Ii trimer, such that the DR, DQ and DP isotypes are contained within separate complexes with Ii. CONCLUSION/SIGNIFICANCE: We propose a structural model of the class II-Ii oligomer and speculate that the pentameric class II-Ii complex is bent towards the cell membrane, inhibiting the binding of additional class II heterodimers to Ii

Citizenship for children: By soil, by blood, or by paternalism?

Do states have a right to exclude prospective immigrants as they see fit? According to statists the answer is a qualified yes. For these authors, self-determining political communities have a prima facie right to exclude, which can be overridden by the claims of vulnerable groups such as refugees and children born in the state’s territory. However, there is a concern in the literature that statists have not yet developed a theory that can protect children born in the territory from being excluded from the political community. For if the self-determining political community has the right to decide who should form the self in the first place, then that right should count against both newcomers by immigration and newcomers by birth. Or so the concern goes. In this essay, I defend statism against this line of criticism and provide a liberal justification for the inclusion of children born within the state’s borders. My account leads to some surprising implication for citizenship law, as well as immigration arrangements in the area of asylum and unauthorized immigration