Mammals, cloning

Normal circulating levels of tPA are low, so that to accomplish this dramatic clot breakdown one would need the amount of tPA contained in 50,000 liters of blood. This is clearly not practical. Instead, the molecule has been cloned and expressed in mammalian cells so that it can be produced in quantity. Using cells from mammals, rather than bacteria, results in a product molecule that has the same folding, internal bonding, and coat of sugar residues as the natural protein. 

More detailed knowledge of the mechanisms of iron absorption from the gastrointestinal tract of mammals has advanced by leaps and bounds in the last few years, with the cloning of key participants at both the apical and basolateral faces of the mucosal endothelial cells. The extraordinarily far-sighted contribution of William Crosby and Marcel Conrad, nearly 40 years ago (Conrad and Crosby, 1963 Crosby, 1963), reminded us of the key role of body iron status in determining the level at which iron absorption will be set within the cells of the crypts of Lieberkiihn when they differentiate and move up to the villus tips to play their key role in... 

Romano, T.A. et al., Molecular cloning and characterization of CD4 in an aquatic mammal, the white whale Delphinapterus leucas, Immuno genetics, 49, 376, 1999. 

Urinary proteins were analyzed by SDS-polyacrylamide gel electrophoresis (PAGE), and a 70-kDa protein was identified as the major component of cat urine (Fig. 4.1 A). Comparative analysis of urinary proteins in several other mammals such as humans, mice, dogs, and cattle did not detect a 70-kDa protein. Therefore, the 70-kDa protein was purified from cat urine and characterized by biochemical methods (Miyazaki, Kamiie, Soeta, Taira and Yamashita 2003). Analysis of tissue distribution indicated that the 70-kDa protein is expressed in the kidney in a tissue-specific manner and secreted from the proximal straight tubular cells of the kidney into the urine (Fig. 4.IB). A full-length cDNA for a 70-kDa protein was cloned from a cat kidney cDNA library. The cDNA clone encoded a polypeptide of 545 amino acid residues. The deduced amino acid sequence shared 47% identity with cat carboxylesterase (CES, EC 3.1.1.1), and contained both the CES family protein motif (EDCLY) and a conserved active site motif (GESAG) associated with... 

Ceramidases are enzymes that cleave the N-acyl linkage of Cer into SPH and free fatty acid. They are an emerging class of enzymes composed of multiple isoforms. Historically, these isoforms have been classified as acid, neutral or alkaline, based on the pH optimum of their activities although some isoforms show activity in a broad range. With the recent cloning of several isoforms from yeast, bacteria, and mammals, a genetical distinction and classification of these enzymes can now be employed. 

Two additional neurotrophins, originally cloned from Xenopus and mammals, respectively, turned out to be counterparts, and this neurotrophin is now termed, NT-4/5. Mammalian NT-4/5 is quite similar to the other neurotrophins but exhibits its own unique neuronal target cell specificities. It is synthesized mainly in the prostate but also in skeletal muscle, placenta and the thymus. 

Comparative (Zoo-FISH) genome mapping and positional cloning of evolutionary chromosome breakpoints in important mammal and vertebral genomes... 

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