LOCALIZATION OF A NEW FERRITIN HEAVY-CHAIN SEQUENCE PRESENT IN HUMAN BRAIN MESSENGER-RNA TO CHROMOSOME-11

Two types of ferritin heavy CH) chain clones have been isolated from c DNA libraries of human fetal and adult brain: one corresponds to the f erritin H chain mRNA that is abundant in liver and is called ''liver-l ike'' brain cDNA; the other contains an additional 279 nucleotide (nt) sequence in the 3'untranslated region and is called brain ferritin H chain cDNA. To map the 279-nt sequence, polymerase chain reaction (PCR ) amplification was carried out using DNA from rodent X human hybrid c ell lines containing single human chromosomes as templates, and oligom eric primers homologous to the 3'end of the 279-nt sequence (primer A) and to a coding sequence just 5' to the 279-nt sequence. Significant PCR product of the size expected from analysis of the brain ferritin H chain cDNA clones and a genomic ferritin H chain clone (487 bp) was g enerated only from hybrid-cell DNA containing human chromosome 11. Thi s PCR product and the ''liver-like'' brain cDNA (lacking the 279-nt se quence) both hybridized to chromosome 11 fragments that are known to d efine the well-characterized functional liver ferritin 11 chain gene a nd a putative pseudogene. preliminary data indicate that primer A (and thus the 279-nt sequence) maps to the functional ferritin H chain gen e fragments, but binding to the pseudogene has not been ruled out.