Differential synthesis and phosphorylation of the alpha-crystallin A and B chains during bovine lens fiber cell differentiation. 1989

R Chiesa, and M J McDermott, and A Spector
Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, New York, NY 10032.

[14C]-amino acids and [32P]-orthophosphate incorporation experiments were carried out in bovine lenses in culture to study the synthesis and phosphorylation of alpha-crystallin A and B polypeptides during differentiation of the lens fiber cells. Following culture, the [14C] or [32P]-labelled alpha-crystallin was isolated by gel filtration chromatography from four regions of the lens corresponding to: A) quiescent epithelial cells, B) dividing epithelial cells and early stages of elongation, C) young elongating fibers, and D) mature fibers from the superficial cortex. The incorporation of label into the alpha-crystallin primary gene products alpha A2 and alpha B2 and their respective phosphorylated forms alpha A1 and alpha B1 was determined by isoelectric focusing and radioautography. Different synthesis and phosphorylation patterns were observed in alpha A and alpha B polypeptides. Synthesis and phosphorylation of the alpha B chain occurs most actively in the epithelial cells, both processes decrease during differentiation and there is no net accumulation of the phosphorylated form alpha B1 in the mature fiber cell. In contrast to the B chain, the A chain synthesis, minimal in the epithelial cell, increases with differentiation. Most striking, the A chain phosphorylation, not detectable in the epithelial cells, increases with differentiation. In the mature fiber cell, the phosphorylated form alpha A1 accounts for one third of the A chain. These observations indicate that the two chains may have different functions. the synthesis and phosphorylation patterns of alpha A suggest a lens-specific function of this polypeptide in the fiber cell and in the terminal differentiation process.(ABSTRACT TRUNCATED AT 250 WORDS)

UI MeSH Term Description Entries
D007525 Isoelectric Focusing Electrophoresis in which a pH gradient is established in a gel medium and proteins migrate until they reach the site (or focus) at which the pH is equal to their isoelectric point. Electrofocusing,Focusing, Isoelectric
D007908 Lens, Crystalline A transparent, biconvex structure of the EYE, enclosed in a capsule and situated behind the IRIS and in front of the vitreous humor (VITREOUS BODY). It is slightly overlapped at its margin by the ciliary processes. Adaptation by the CILIARY BODY is crucial for OCULAR ACCOMMODATION. Eye Lens,Lens, Eye,Crystalline Lens
D010766 Phosphorylation The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety. Phosphorylations
D002417 Cattle Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor. Beef Cow,Bos grunniens,Bos indicus,Bos indicus Cattle,Bos taurus,Cow,Cow, Domestic,Dairy Cow,Holstein Cow,Indicine Cattle,Taurine Cattle,Taurus Cattle,Yak,Zebu,Beef Cows,Bos indicus Cattles,Cattle, Bos indicus,Cattle, Indicine,Cattle, Taurine,Cattle, Taurus,Cattles, Bos indicus,Cattles, Indicine,Cattles, Taurine,Cattles, Taurus,Cow, Beef,Cow, Dairy,Cow, Holstein,Cows,Dairy Cows,Domestic Cow,Domestic Cows,Indicine Cattles,Taurine Cattles,Taurus Cattles,Yaks,Zebus
D002454 Cell Differentiation Progressive restriction of the developmental potential and increasing specialization of function that leads to the formation of specialized cells, tissues, and organs. Differentiation, Cell,Cell Differentiations,Differentiations, Cell
D002850 Chromatography, Gel Chromatography on non-ionic gels without regard to the mechanism of solute discrimination. Chromatography, Exclusion,Chromatography, Gel Permeation,Chromatography, Molecular Sieve,Gel Filtration,Gel Filtration Chromatography,Chromatography, Size Exclusion,Exclusion Chromatography,Gel Chromatography,Gel Permeation Chromatography,Molecular Sieve Chromatography,Chromatography, Gel Filtration,Exclusion Chromatography, Size,Filtration Chromatography, Gel,Filtration, Gel,Sieve Chromatography, Molecular,Size Exclusion Chromatography
D003459 Crystallins A heterogeneous family of water-soluble structural proteins found in cells of the vertebrate lens. The presence of these proteins accounts for the transparency of the lens. The family is composed of four major groups, alpha, beta, gamma, and delta, and several minor groups, which are classed on the basis of size, charge, immunological properties, and vertebrate source. Alpha, beta, and delta crystallins occur in avian and reptilian lenses, while alpha, beta, and gamma crystallins occur in all other lenses. Lens Proteins,Crystallin,Eye Lens Protein,Lens Protein, Eye,Protein, Eye Lens,Proteins, Lens
D000596 Amino Acids Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins. Amino Acid,Acid, Amino,Acids, Amino
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D001345 Autoradiography The making of a radiograph of an object or tissue by recording on a photographic plate the radiation emitted by radioactive material within the object. (Dorland, 27th ed) Radioautography

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