Pigmented melanoma cells and cultured melanocytes express a differentiation-related glycoprotein designated as pigmentation-associated antigen (PAA) of Mr 70,000-80,000. As described previously, PAA was initially defined by reactivity with antibodies in the serum of a patient with melanoma. Here we describe the production and characterization of a mouse monoclonal antibody to PAA. This antibody (TA99, an IgG2a) was shown by sequential immunoprecipitation experiments to react with the same component as the human antibody. Ab TA99 immunoprecipitated PAA from lysates of cells radiolabeled with [35S]methionine, [3H]glucosamine, [3H]fucose, and [3H]mannose as well as 125I. Using Ab TA99, the distribution of PAA was examined in frozen sections of 19 normal tissues and quantitatively in 68 tissue culture cell lines. In frozen sections, only melanin-containing cells were positive, including epithelial cells in the basal layer of the epidermis, in which pigment originates from melanocytes by transfer of melanosomes, and pigmented cells of the eye. In tissue culture cell lines, only pigmented melanoma cells were positive. PAA is an intracellular antigen, with a distribution very similar to that of melanosomes. This evidence confirms the close association of PAA with melanin production, and suggests that PAA may be a melanosome component. PAA was shown to be different from tyrosinase, the enzyme involved in melanin synthesis, but it was found to be identical to the previously recognized glycoprotein, gp75, characteristic of pigmented melanomas and melanocytes.

We previously described a diverse family of sulfated anionic N-linked oligosaccharides released by peptide: N-glycosidase F (PNGaseF) from calf pulmonary artery endothelial (CPAE) cells (Roux, L., Holoyda, S., Sundblad, G., Freeze, H. H., and Varki, A. (1988) J. Biol. Chem. 263, 8879 -8889). Since a major fraction of the intact lung consists of endothelial cells, we reasoned that bovine lung might be a rich source of similar molecules. Total N-linked oligosaccharides from bovine lung acetone powder were released by PNGaseF, labeled by [ 3 H]NaBH 4 reduction, and the anionic fractions were studied with a variety of techniques. The sugar chains with lesser negative charge (designated Class I) share several properties of conventional multiantennary complex-type chains. However, unlike the case with CPAE cells, sialic acids account only for a minority of the anionic properties and only a small proportion carry sulfate esters. A variety of different treatments indicate that most of the unexplained negative charge is due to multiple carboxylic acid groups. Resistance to ␤-glucuronidase and ␣-iduronidase suggests that these may be previously undescribed modifications of mammalian oligosaccharides. The most highly charged N-linked chains (designated Class II) are more similar in general structure to the corresponding ones from CPAE cells, although relatively more abundant. Their high charge is primarily due to chondroitin sulfate, heparin/heparan sulfate, or keratan sulfate glycosaminoglycan chains. Sequential digestion studies suggest that a significant proportion of these molecules have more than one type of glycosaminoglycan chain associated with them. Compositional analysis indicates the presence of xylose residues in Class II, but not Class I molecules. However, unlike the case with conventional glycosaminoglycans, these residues are not at the reducing terminus.Most The anionic character of most known N-linked oligosaccharides is due to the presence of sialic acids (1, 2). However, negative charge in such molecules can also be due to phosphate esters (3, 4), sulfate esters (5-12), or, possibly, uronic acids (13-16). Unlike sialylated chains, the other types of anionic molecules are considered rare, being reported only in small amounts and/or only on certain proteins. By metabolic labeling with [ 1 (17), we previously identified and characterized a diverse family of anionic N-linked oligosaccharides in CPAE cells, a calf pulmonary artery endothelial cell line (10, 11). These sugar chains were separated by size and charge into two general classes. "Class I" was composed of molecules bearing various combinations of primary sulfate esters and sialic acids, while "Class II" molecules carried sequences susceptible to cleavage by glycosaminoglycan-degrading enzymes. About half of the negative charge on the sulfated Class I molecules could be attributed to GlcNAc-6-sulfate units at a position subterminal to sialic acid and ␤-galactose. In the case of Class II molecules, most of the negative charge was susceptible to hepar...

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Infant formulas (IFs) can be defined as substitutes for human milk, which are mostly based on cow milk proteins. For sustainability reasons, alternative to animal proteins in food have to be considered. Plant proteins offer interesting nutritional and functional benefits for the development of innovative IFs. However, the behaviour of these proteins during processing and storage must ensure the physical stability and ability to reconstitution of IF powders, and that needs to be tested. This work aimed to study how a partial substitution of dairy proteins by plant proteins may influence the functional properties of 1 st age IFs. Three IFs were developed at a semi-industrial scale using two different processing routes. The IFs composition was identical, except that 50% of the proteins were whey proteins in the "reference IF" (RIF), and pea or faba bean proteins in the "plant IFs" (PIF and FIF, respectively). After reconstitution, the three IFs result in similarly stable emulsions with equivalent free fat release. In comparison to RIF, PIF and FIF were difficult to disperse, thus conducting to remaining insoluble particles. Thus, the protein source greatly influences IFs properties, and process parameters need to be adapted for each formulation to meet IFs quality criteria.

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