抄録
Formation of metaphase chromosome is well organized process to ensure faithful and proper segregation of genomic information into two daughter cells. However, the chromosome higher structure remains unclear partly because of the lack in the information on protein constituent of chromosomes, namely the proteome of chromosomes. Then, we performed the proteome analyses of human metaphase chromosome. In addition to the proteome of highly purified chromosomes which is composed of 107 chromosome proteins, biochemical behaviors of each protein were clarified. Furthermore, comparative proteome analyses among chromosomes from different isolation methods and different types of cell lines enabled us to establish chromosome four-layer model and to classify chromosome proteins into four different groups, chromosome structural proteins (CSPs), chromosome peripheral proteins (CPPs), chromosome coating proteins (CCPs), and chromosome fibrous proteins (CFPs). CSPs amount to 89.3 % of chromosome proteins. CSPs are proteins which are localized to chromosomes in vivo and found after thorough purification such as histones, HMGs, topoIIa, and condensins. CSPs are therefore most likely essential for a chromosome structure. Centromeric, telomeric, chromosome passenger proteins are also classified into CSPs group. CPPs group is composed of proteins which amount to 3.1 % of chromosome proteins and are localized to chromosome periphery. A part of CPPs, like nucleolin and ASURA, were confirmed by us to contribute accurate chromosome segregation during mitosis. CCPs are proteins attached to chromosomes during isolation process, thus are not intrinsic chromosome proteins. CFPs are cytoskeleton proteins, such as β-actin and vimentin, having nature to form fibers. CFPs are surrounding mitotic chromosomes in vivo and are tightly bound to isolated chromosomes unevenly. Consequently, a data set of protein constituent of chromosomes now offer lead for further studies on chromosome structure. Chromosome proteomes and the individual proteins known so far are reviewed in relation to the chromosome structure.
