Nucleoplasmin cDNA sequence reveals polyglutamic acid tracts and a cluster of sequences homologous to putative nuclear localization signals.

Abstract

Parks Road, Oxford OXI 3PS, UK Communicated by R. A.Laskey Nucleoplasmin is the most abundant protein in the Xenopus oocyte nucleus. It is involved in histone storage and chromatin assembly and it has been used extensively to study the transport of proteins into the cell nucleus. We have isolated X gtll phage containing nucleoplasmin cDNA and have determined the sequence of the entire protein coding region of 200 amino acids for one of the two genes. The translation product of the sp6 transcript of this cDNA has the same electrophoretic mobility as nucleoplasmin and is able to form pentamers. The protein sequence shows remarkable clusters of charged residues including a long polyglutamic acid tract which presumably constitutes the histone binding site. The short C-terminal domain which specifies nuclear entry contains four regions which are homologous to putative nuclear localization signals including two regions of homology to the nuclear migration signal of SV40 large T antigen.

An abundant nucleolar phosphoprotein is associated with ribosomal DNA in Tetrahymena macronuclei.

“…The polypeptide, termed Nopp52, exhibits a highly modular domain structure with alternating acidic/basic repeats distinguishing its amino-terminal half. A similar organization of alternating acidic/basic stretches has also been described in many nucleolar proteins including nucleolin, NSR1, NpI46, Noppl40, and B23/No38 (Dingwall et al, 1987;Lapeyre et al, 1987;Lee et al, 1991;Meier and Blobel, 1992;Shan et al, 1994). Many of this class of polypeptides, including Nopp52, have aberrantly slow mobility in SDS gels and are phosphorylated by CKII.…”

“…Therefore, these stretches are likely to be highly negatively charged in vivo. The difference between the predicted molecular mass of Nopp52 (52 kDa) and the apparent molecular weight on SDS gels (65 kDa) is characteristic of similar polypeptides that are phosphorylated and highly charged (Dingwall et al, 1987;Lapeyre et al, 1987;Meier and Blobel, 1992).…”

NAP‐I is a functional homologue of TAF‐I that is required for replication and transcription of the adenovirus genome in a chromatin‐like structure

“…Nucleoplasmin and N1, which associate with H2A and H2B and with H3 and H4, respectively, were isolated from the eggs of Xenopus laevis. They can function as molecular chaperones to promote nucleosome assembly and are involved in histone storage (Laskey et al 1978;Kleinschmidt & Franke 1982;Kleinschmidt et al 1986;Dilworth et al 1987;Dingwall et al 1987;Kleinschmidt & Seiter 1988). Chromatin assembly factor (CAF-I) binds histones and promotes chromatin assembly during DNA replication in vitro (Stillman 1986;Smith & Stillman 1989Kaufman et al 1995).…”

A nuclear factor containing the leucine-rich repeats expressed in murine cerebellar neurons.

“…However, such an acidic cluster is not unique in LANP. Nucleoplasmin, the most abundant protein in the Xenopus oocyte nucleus, contains an acidic cluster at the C-terminal region (27). Like LANP, this protein has putative nuclear localization signals inside the cluster.…”