In order to identify and characterize structural components in the nuclear membrane of Saccharomyces cerevisiae which show a cell-cycle dependent regulation, we have undertaken a combined biochemical/immunofluorescence microscopy approach. Antisera raised against nuclear membrane proteins from yeast lead to the identification of a 40 kDa membrane protein which cofractionated with nuclei upon cell fractionation. This 40 kDa membrane protein partitioned into the Triton X-114 phase and was not extracted from purified nuclei at alkaline pH. Using affinity-purified antibodies against this protein, the antigen was localized at the nuclear periphery suggesting that it is an integral constituent of the nuclear envelope. However, the 40 kDa antigen revealed a heterogenous distribution within the nuclear membrane: in indirect immunofluorescence microscopy, nuclei isolated from an asynchronously growing yeast culture showed either no immunodetectable antigen or contained it in a cap-, dot- or ring-like conformation. Using synchronized yeast cultures, we could demonstrate cell-cycle dependent changes of concentration and localization of the 40 kDa protein within the nuclear envelope.

• PMID: 16320457
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Journal Article

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Schimmang T, Hurt EC

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