Faithful chaperones

This review describes the properties of some rare eukaryotic chaperones that each assist in the folding of only one target protein. In particular, we describe (1) the tubulin cofactors, (2) p47, which assists in the folding of collagen, (3) α-hemoglobin stabilizing protein (AHSP), (4) the adenovirus L4-100 K protein, which is a chaperone of the major structural viral protein, hexon, and (5) HYPK, the huntingtin-interacting protein. These various-sized proteins (102–1,190 amino acids long) are all involved in the folding of oligomeric polypeptides but are otherwise functionally unique, as they each assist only one particular client. This raises a question regarding the biosynthetic cost of the high-level production of such chaperones. As the clients of faithful chaperones are all abundant proteins that are essential cellular or viral components, it is conceivable that this necessary metabolic expenditure withstood evolutionary pressure to minimize biosynthetic costs. Nevertheless, the complexity of the folding pathways in which these chaperones are involved results in error-prone processes. Several human disorders associated with these chaperones are discussed

ESR in a Heavy-Fermion Alloy (U Be

We have determined the ESR properties of UBe13 doped with dilute local moments of Er, Dy, or Gd over the temperature region where there is a large variation in the enhanced specific heat. We find that neither the enhancement, the temperature variation, nor any other anomalous behavior appears to be mirrored in the ESR data. We suggest that this unexpected result must be incorporated into current models of heavy-fermion systems. © 1985 The American Physical Society