MOLECULAR GENETICS OF THE CARBONIC ANHYDRASES

碳酸酐酶（CA）和CA相关基因构成哺乳动物的 CA多基因家族代表了一个由八个基因组成的非常多样化的群体。 这些基因的表达范围从单个组织（例如，CA VI在 唾液腺）的某些细胞中表达， 组织（例如，CA II）。 在细胞中，它们存在于：细胞质（CA I，II，III），与膜相关（CA IV）， 唾液腺（CA VI），.或线粒体的内部基质。 因为到 关于这些不同CA的特定细胞作用知之甚少 同工酶，基因打靶技术将用于研究 通过观察不同基因产物的行为， 发育、形态或生理影响 小鼠的基因失活。 最初，这些基因将被研究， 灭活最有可能产生信息性结果。 这些措施是： CA III（主要在骨骼肌中表达）、CA IV（膜- CA V（线粒体）和高度进化保守的 CA相关蛋白。 建议的具体目标如下： 以制造靶向构建体并产生具有以下突变的ES细胞系： 四个选择的小鼠基因，（2）产生纯合子小鼠缺陷 对于每个基因，（3）绘制CA基因的染色体位置 尚未映射的（CA IV，CA V和CARP），以及（4）生成 多个CA基因联合缺陷的小鼠，以检测 职能重叠。 如果时间许可，我们会进行类似的研究 其他CA基因，CA I，CA VI和CA VII。 除了 阐明基因产物的功能，CA的其他方面 缺陷小鼠将非常有用。 例如，如果a的表型 纯合CA缺陷小鼠类似于遗传性人类疾病， 未知的遗传病因，有可能是相同的CA缺乏症， 从而提供了一种有用的动物模型 对于人类疾病。 此外，确定 这些基因的染色体位置是自发的， 特定CA基因中的突变可能导致一种经典的 小鼠的表型突变体。 这种自发突变，无论 完全缺乏或部分丧失活性，可提供 受影响基因的生物学功能。

The carbonic anhydrase (CA) and CA-related genes comprising the mammalian CA multigene family represent a remarkably diverse group of eight genes. These genes range from in their expression single tissues (e.g., CA VI in salivary glands) to their expression in certain cells of virtually all tissues (e.g., CA II). In the cell, they are found in: the cytoplasm (CA I, II, III), associated with membranes (CA IV), the secretory granules of salivary glands (CA VI),. or the inner matrix of mitochondria. Because so little is known about the specific cellular roles of these different CA isozymes, the technique of gene targeting will be used to investigate the functions of the different gene products by observing the behavioral, developmental, morphological or physiological effects produced by specific gene inactivations in mice. Initially, those genes will be studied whose inactivations are most likely to produce informative results. These are: CA III (expressed primarily in skeletal muscle), CA IV (membrane- associated), CA V (mitochondria), and the highly evolutionarily-conserved CA-related protein, CARP. The following specific aims are proposed: (l) to make targeting constructs and generate ES cell lines with mutations in the four selected mouse genes, (2) to generate homozygous mice deficient for each of the genes, (3) to map the chromosomal location of the CA genes that are not already mapped (CA IV, CA V and CARP), and (4) to generate mice with combined deficiencies for multiple CA genes in order to detect overlapping functions. If time permits, similar studies will be carried out on the other CA genes, CA I, CA VI and CA VII. In addition to elucidating the functions of the gene products, other aspects of the CA deficient mice will be highly useful. For example, if the phenotype of a homozygous CA deficient mouse is similar to an inherited human disease of unknown genetic etiology, it is possible that the same CA deficiency is responsible for the human disorder thereby providing a useful animal model for the human disease. Also, an important reason for determining the chromosomal locations of these genes is the possibility that a spontaneous mutation in a specific CA gene may be responsible for one of the classical phenotypic mutants of the mouse. Such spontaneous mutations, whether complete deficiencies or partial losses of activity, can provide insight into the biological function of the affected gene.