CLN5

Ceroid-lipofuscinosis neuronal protein 5 is a protein that in humans is encoded by the CLN5 gene.

The neuronal ceroid lipofuscinoses (CLN or NCL) are a group of autosomal recessive, progressive encephalopathies in children. They are characterized by psychomotor deterioration, visual failure, and the accumulation of autofluorescent lipopigment in neurons and other cell types. The main childhood forms are the infantile type (Santavuori-Haltia disease; MIM 256730), the late infantile type (Jansky-Bielschowsky disease; MIM 204500), and the juvenile type (Batten disease; MIM 204200) based on the age of onset, clinical course, neurologic and ophthalmologic findings, and ultrastructural analysis (Carpenter et al., 1977 [PubMed 193610]).[supplied by OMIM]

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Cln3

G1/S-specific cyclin Cln3 is a protein that is encoded by the CLN3 gene. The Cln3 protein is a budding yeast G1 cyclin that controls the timing of Start, the point of commitment to a mitotic cell cycle. It is an upstream regulator of the other G1 cyclins, and it is thought to be the key regulator linking cell growth to cell cycle progression. It is a 65 kD, unstable protein; like other cyclins, it functions by binding and activating cyclin-dependent kinase (CDK).

Cln3 in Start regulation

Cln3 regulates Start, the point at which budding yeast commit to the G1/S transition and thus a round of mitotic division. It was first identified as a gene controlling this process in the 1980s; research over the past few decades has provided a mechanistic understanding of its function.

Identification of CLN3 gene

The CLN3 gene was originally identified as the whi1-1 allele in a screen for small size mutants of Saccharomyces cerevisiae (for Cln3's role in size control, see below). This screen was inspired by a similar study in Schizosaccharomyces pombe, in which the Wee1 gene was identified as an inhibitor of cell cycle progression that maintained normal cell size. Thus, the WHI1 gene was at first thought to perform a size control function analogous to that of Wee1 in pombe. However, it was later found that WHI1 was in fact a positive regulator of Start, as its deletion caused cells to delay in G1 and grow larger than wild-type cells. The original WHI1-1 allele (changed from whi1-1 because it is a dominant allele) in fact contained a nonsense mutation that removed a degradation-promoting PEST sequence from the Whi1 protein and thus accelerated G1 progression.WHI1 was furthermore found to be a cyclin homologue, and it was shown that simultaneous deletion of WHI1—renamed CLN3—and the previously identified G1 cyclins, CLN1 and CLN2, caused permanent G1 arrest. This showed that the three G1 cyclins were responsible for controlling Start entry in budding yeast.

CLN3

Battenin is a protein that in humans is encoded by the CLN3 gene located on chromosome 16.

Function

Battenin is involved in lysosomal function. Many alternatively spliced transcript variants have been found for this gene.

Clinical significance

Mutations in this gene, as well as other neuronal ceroid-lipofuscinosis (CLN) genes, cause neurodegenerative diseases commonly known as Batten disease, also known as Juvenile Neuronal Ceroid Lipofuscinosis (JNCL) or Juvenile Batten disease.

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