THE N-TERMINAL TPR REGION IS THE FUNCTIONAL DOMAIN OF SSN6, A NUCLEAR PHOSPHOPROTEIN OF SACCHAROMYCES-CEREVISIAE
THE N-TERMINAL TPR REGION IS THE FUNCTIONAL DOMAIN OF SSN6, A NUCLEAR PHOSPHOPROTEIN OF SACCHAROMYCES-CEREVISIAE
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DOI：
10.1128/mcb.10.9.4744
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发表时间：
1990-09-01
影响因子：
5.3
通讯作者：
CARLSON, M
中科院分区：
文献类型：
--
作者：
SCHULTZ, J;MARSHALLCARLSON, L;CARLSON, M
SSN 6蛋白在酵母中作为多种基因的负调节剂发挥作用，并且是正常生长、交配和孢子形成所必需的。它是由重复的氨基酸序列，TPR（tetratricopeptide repeat）基序定义的家族成员。在这里，我们使用特异性抗体来鉴定和表征SSN 6蛋白。SSN 6和双功能SSN 6-β-半乳糖苷酶融合蛋白通过免疫荧光染色定位于细胞核中。含有TPR单位的蛋白质的N-末端三分之一被鉴定为对SSN 6功能重要的区域。分析4个无义等位基因，分离作为基因内抑制anssn 6：：URA 3插入，揭示了TPR单元7后截短的多肽提供SSN 6功能。缺失分析表明，需要TPR单位，但10个TPR单位中的4个就足够了。此外，缺失研究表明，三个非常长的，均匀的多聚谷氨酰胺和聚（谷氨酰胺-丙氨酸）的道是不连续的。先前的遗传证据表明SSN 6蛋白是SNF 1蛋白激酶的可能靶点。在这里，我们表明，SSN 6的C末端在体内被磷酸化，SNF 1激酶是不负责大部分的磷酸化。最后，SSN 6对微型染色体的维持有适度的影响。
The SSN6 protein functions as a negative regulator of a variety of genes inSaccharomyces cerevisiaeand is required for normal growth, mating, and sporulation. It is a member of a family defined by a repeated amino acid sequence, the TPR (tetratricopeptide repeat) motif. Here, we have used specific antibody to identify and characterize the SSN6 protein. Both SSN6 and a bifunctional SSN6-P-galactosidase fusion protein were localized in the nucleus by immunofluorescence staining. The N-terminal one-third of the protein containing the TPR units was identified as the region that is important for SSN6 function. Analysis of four nonsense alleles, isolated as intragenic suppressors of anssn6::URA3insertion, revealed that polypeptides truncated after TPR unit 7 provide SSN6 function. Deletion analysis suggested that TPR units are required but that 4 of the 10 TPR units are sufficient. In addition, deletion studies indicated that three very long, homogeneous tracts of polyglutamine and poly(glutamine-alanine) are dispensable. Previous genetic evidence suggested the SSN6 protein as a possible target of the SNF1 protein kinase. Here, we show that the C terminus of SSN6 is phosphorylated in vivo and that the SNF1 kinase is not responsible for most of the phosphorylation. Finally, SSN6 has a modest effect on the maintenance of minichromosomes.