3 SUBSETS OF GENES WHOSE TISSUE-SPECIFIC EXPRESSION IS SEX AND AGE-DEPENDENT CAN BE IDENTIFIED WITHIN THE RAT ALPHA(2U)-GLOBULIN FAMILY

The rat alpha(2v)-globulins are encoded by a multigene family whose 20 -25 members are subjected to multihormonal regulation that is dependen t upon the sex of the animal, the developmental stage and the tissue b eing examined. Using RT-PCR and diagnostic restriction analysis of the products, we have examined the specificity of the expression of diffe rent members of the gene family. All family members can be classified into three subsets, depending on how the amplified cDNA responds io di gestion with ApaLl, Sstl and Vspl. Subset A contains the restriction s ites for both ApaLl and SsA but not Vspl and typifies the genes expres sed in the salivary glands of both mature and juvenile animals of both sexes, where ii is the only subset expressed. This subset of genes al so accounts for all the transcripts observed in the kidneys and mammar y glands of juvenile males. Although subset A was represented in the t ranscript populations of all the other tissues examined, iis proportio n relative to the total varied greatly. The two other subsets were sub set V, which contains only the restriction site for Vspl, and subset N , which lacks all three restriction sites. in all the other tissues ex amined, two or all three of the subsets were expressed, usually in a m anner that was unique to the sex and age of the tissue in question. Th e proportion of each of the three alpha(2v)-globulin subsets in the al pha(2v)-globulin gene family was determined by quantitation of the res triction products of amplified genomic DNA. interestingly, the most pr evalent subset in the genome (N) has the most limited tissue expressio n pattern, but is found in liver and preputial glands, the tissues exp ressing the most substantial quantities of alpha(2v)-globulin. These r esults indicate the complexity of the regulation of the alpha(2v)-glob ulins and point io the necessity for gene specific analyses if the exp ression of the family is to be understood in molecular terms. (C) 1997 Wiley-Liss, Inc.