CD44 expression results in the synthesis of unusual RNAs and multiple protein species containing core polypeptide sequences.

Several cDNA clones encoding portions of the primate CD44 molecule have been isolated. Nonprototypic clones are moderately abundant in a cDNA library, with four unusual clones identified out of the 25 examined. Two of these clones appear to be the result of incomplete RNA splicing events. The baboon genome appears to contain multiple CD44 related sequences. Cell surface CD44 is expressed in greatly differing amounts in different tissues. These levels are generally paralleled by CD44 mRNA levels. Analysis of the relationship between the 90 kDa and 180-200 kDa with two polypeptide specific antisera indicates that these two antigens share extensive amino acid similarity and are likely to be differentially modified versions of the same gene product.