U. Kuhn et T. Pieler, XENOPUS POLY(A) BINDING-PROTEIN - FUNCTIONAL DOMAINS IN RNA-BINDING AND PROTEIN-PROTEIN INTERACTION, Journal of Molecular Biology, 256(1), 1996, pp. 20-30
Subsets of the four RNA binding domains (RBD 1 to 4) in the Xenopus po
ly-adenylate binding protein (PABP) have distinct affinities and speci
ficities for RNA. RBDs 1 plus 2 exhibit RNA affinity and selectivity e
qual to the wild-type (WT) protein. RBDs 3 plus 4 have distinct select
ivity and about ten-fold reduced affinity for A(23), and the isolated
RBDs 2 or 3 or 4 exhibit about 100-fold reduced affinity for A(23) in
comparison to WT. For the full-length protein, independent RNA contact
s have been mapped by UV crosslinking with RBDs 1/2 and RBDs 3/4. The
carboxy-terminal, non-RBD portion of the protein does not contribute t
o RNA affinity or selectivity, but confers homodimerization activity o
n PABP. RBDs 3 and 4 cooperate with the C terminus to gain poly(A) org
anizing activity, i.e. the ability to form an RNP with multiple, regul
arly spaced copies of PABP on a poly(A) substrate. (C) 1996 Academic P
ress Limited.