Insect vitellogenin and yolk protein receptors ( @entity11673 /YPR) are newly discovered members of the @entity754 ( @entity754 ) family, which is characterized by a highly conserved arrangement of repetitive modular elements homologous to functionally unrelated proteins. The insect @entity11673 /YPRs are unique in having two clusters of complement-type @entity462 -rich (class A) repeats or modules, with five modules in the first cluster and seven in the second cluster, unlike classical LDLRs which have a single seven-module cluster, vertebrate VgRs and very low density lipoprotein receptors ( @entity28427 ) which have a single eight-module cluster, and @entity754 -related proteins (LRPs) and megalins which have four clusters of 2-7, 8, 10, and 11 modules. Alignment of clusters across subfamilies by conventional alignment programs is problematic because of the repetitive nature of the component modules which may have undergone rearrangements, duplications, and deletions during evolution. To circumvent this problem, we "fingerprinted" each class A module in the different clusters by identifying those @entity1522 that are both relatively conserved and relatively unique within the cluster. Intercluster reciprocal comparisons of fingerprints and aligned sequences allowed us to distinguish four cohorts of modules reflecting shared recent ancestry. All but two of the 57 modules examined could be assigned to one of these four cohorts designated A, B, C, and D. Alignment of clusters based on modular cohorts revealed that all clusters are derived from a single primordial cluster of at least seven modules with a consensus arrangement of CDCADBC. All extant clusters examined are consistent with this consensus, though none matches it perfectly. This analysis also revealed that the eight-module clusters in vertebrate VgRs, insect @entity11673 /YPRs, and @entity8993 /megalins are not directly homologous with one another. Assignment of modules to cohorts permitted us to properly align 32 class A clusters from all four @entity754 subfamilies for phylogenetic analysis. The results revealed that smaller one-cluster and two-cluster members of the family did not originate from the breakup of a large two-cluster or four-cluster receptor. Similarly, the @entity8993 /megalins did not arise from the duplication of a two-cluster insect @entity11673 /YPR-like progenitor. Rather, it appears that the multicluster receptors were independently constructed from the same single-cluster ancestor.

Ligand-binding domains in vitellogenin receptors and other LDL-receptor family members share a common ancestral ordering of XXXX -rich repeats.

@entity754 :: ('3949', 'Gene') :: ['low-density lipoprotein receptor', 'LDLR'] @entity1522 :: ('CHEBI:33709', 'Chemical') :: ['amino acids'] @entity462 :: ('MESH:D003545', 'Chemical') :: ['cysteine'] @entity8993 :: ('4035', 'Gene') :: ['LRP'] @entity11673 :: ('654', 'Gene') :: ['VgR'] @entity28427 :: ('7436', 'Gene') :: ['VLDLR']
@entity462 :: (MESH:D003545,Chemical) :: ['cysteine']
