The Variable Lymphocyte Receptors (VLRs) of Lampreys Represent a Highly

Multiple Choice

The variable lymphocyte receptors (VLRs) of lampreys represent a highly diverse set of proteins with structural similarity to the mammalian Toll-like receptors. Yet the VLRs and the lymphocytes that produce them are thought to be components of the lamprey's adaptive immune system. This is because:

A) The VLRs are highly diverse and have been shown to bind to pathogens.
B) Both membrane-bound and secreted forms of VLRs are found in the lampreys.
C) VLR coding genes are formed by DNA rearrangement events.
D) VLRs are clonally distributed such that each lymphocyte expresses only one form of VLR.
E) VLR gene rearrangements occur by a process similar to gene conversion.