Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cell differentiation during spermatogenesis in the rat has been analyzed in terms of the formation of specific "marker" enzymes. Hyaluronidase and other acrosomal enzymes are formed in spermatids according to a highly predictable time schedule which may be termed a "molecular biological clock". The acrosomal enzymes beta-galactosidase and N-acetyl-beta-glucosaminidase exist as isoenzyme forms distinct from enzymes with similar substrate specificities in the lysosomes of precursor cells. Differentiation of spermatids thus involves the loss of gene expression for lysosomal enzymes and the activation of genes for acrosomal isoenzymes. Spermatogenesis is characterized by the sequential loss of expression of many genes, as evidenced by the loss of beta-glucuronidase in the differentiation of spermatogonia to spermatocytes, and the loss of uridine diphosphatase activity in the differentiation of spermatocytes to spermatids. The apparent absence of ornithine decarboxylase activity from spermatids suggests a dependence of these cells upon Sertoli cells for the provision of putrescine and/or spermidine. Such biochemical cooperativity among germinal cells may be necessary as the genes of spermatids are repressed and late spermatids become metabolically inactive. Spermatogenesis is also characterized by changes in the cellular content and rates of synthesis and phosphorylation of specific acidic chromatin proteins. It is hypothesized that these proteins may participate in the activation or repression of genes during spermatogenesis.
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PMID:Gene activation during spermatogenesis. 112 12

We have recently described a new locus, Hyal-1, which determines hyaluronidase variants in mouse serum. On the basis of segregation in recombinant inbred and congenic strains, Hyal-1 was tentatively assigned to chromosome 9 (Fiszer-Szafarz and De Maeyer, '89). In the present study we have performed a linkage analysis of Hyal-1 using 156 backcross progeny of an interspecies cross of laboratory mice and Mus Spretus. Linkage was tested to two anchor loci on chromosome 9: d (dilute, a coat color locus) and Bgl-s (a locus controlling beta-galactosidase activity). The gene order (from centromere) with intervening percentage recombination is d-16.6 (+/- 2.9)-Hyal-1-10.9 (+/- 2.4)-Bgl-s, indicating close linkage to H-7 and Fv-2.
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PMID:Linkage analysis of the murine Hyal-1 locus on chromosome 9. 202 49

It has been suggested that intracellular Hyal-1 (hyaluronidase-1), which is considered a lysosomal enzyme, originates via endocytosis of the serum enzyme. To test this proposal we have investigated the uptake and intracellular distribution of rhHyal-1 (recombinant human Hyal-1) by mouse liver, making use of centrifugation methods. Experiments were performed on wild-type mice injected with 125I-labelled rhHyal-1 and on Hyal-1-/- mice injected with the unlabelled enzyme, which were killed at various times after injection. Activity of the unlabelled enzyme was determined by zymography. Intracellular distribution of Hyal-1 was investigated by differential and isopycnic centrifugation. The results of the study indicated that rhHyal-1 is endocytosed by the liver, mainly by sinusoidal cells, and follows the intracellular pathway described for many endocytosed proteins that are eventually located in lysosomes. However, Hyal-1 endocytosis has some particular features. First, endocytosed rhHyal-1 is quickly degraded. Secondly, its distribution, as analysed by differential centrifugation, differs from the distribution of beta-galactosidase, taken as the reference lysosomal enzyme. Further analysis by isopycnic centrifugation in a sucrose gradient shows endocytosed rhHyal-1 behaves like beta-galactosidase shortly after injection. However the Hyal-1 distribution is markedly less affected than beta-galactosidase, following a prior injection of Triton WR-1339, which is a specific density perturbant of lysosomes. The behaviour in centrifugation of endogenous liver Hyal-1, identified by hyaluronan zymography, exhibits some similarity with the behaviour of the endocytosed enzyme, suggesting that it could originate from endocytosis of the serum enzyme. Overall, these results can be explained by supposing that active endocytosed Hyal-1 is mainly present in early lysosomes. Although its degradation half-time is short, Hyal-1 could exert its activity due to a constant supply of active molecules from the blood.
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PMID:Endocytosis of hyaluronidase-1 by the liver. 2057 8