Nuclear proteins and the onset of cell proliferation in root meristems ofPisum sativum: QP47 a novel acidic protein

Abstract

A protein named QP47 has been purified from quiescent nuclei of root meristems of Pisum sativum, and used to prepare a polyclonal antibody. Immunolocalization of this protein with fluorescent probes revealed a nuclear distribution of thread-like structures. However, the relationship between the distribution of QP47 immunofluorescence and the structural organization of the chromatin required further investigation. The decrease in content of this protein in the nuclei of embryo cells seems to be correlated with the transition from quiescence to proliferation. QP47 degradation seems to depend upon an increase in the state of its phosphorylation. This protein is not present in normally proliferating cells, or in cells whose cell proliferation has been arrested by starvation or differentiation. It is hypothesized that QP47 may be required specifically during the quiescent period for specific structural organization of the chromatin.

Structure and Function of Roots

“…In fact, the 47 kDa protein was recognized (data not 295 shown) by the QP47 polyclonal antibody prepared previously (Chiatante and Onelli, 1993). In fact, the 47 kDa protein was recognized (data not 295 shown) by the QP47 polyclonal antibody prepared previously (Chiatante and Onelli, 1993).…”

“…We had shown previously that a considerable amount of QP47 was present in nuclei of meristematic root cells after 6 h of imbibition (Chiatante and Onelli, 1993). In the same paper, the comparison of the QP47 content at different times of germination demonstrated that the amount of this nuclear protein must decrease to an undetectable level before cell proliferation can be resumed.…”

“…When the conserved sequences of the repeat unit of some known LEA proteins were compared with the only stretch of sequence of QP47 identified so far (Chiatante and Onelli, 1993) no homology was found.…”

“…For this purpose, QP47 polyclonal Ab had been used previously to study the immunolocalization ofthis protein in nuclei during seed germination (Chiatante and Onelli, 1993). For this purpose, QP47 polyclonal Ab had been used previously to study the immunolocalization ofthis protein in nuclei during seed germination (Chiatante and Onelli, 1993).…”

“…In my laboratory, a novel nuclear protein named QP47 has been purified which might play such a role (Chiatante and Onelli, 1993). Because of the peculiar molecular organization of the nucleus, it would be interesting to ascertain the protective mechanisms devised to survive desiccation and to maintain the integrity of the DNA molecule.…”