The region 3 ' to C alpha 1 gene of human IG heavy chain displays a polymorphic duplicated sequence and encodes an RNA associated with polysomes

A highly spread polymorphism flanking the 3 C alpha 1 human IG heavy chain gene was identified. This polymorphism allowed the detection of an internal duplication within the 3' flanking region of both C alpha 1 and C alpha 2. This region has a regulatory function with four enhancer structures also present at the 3' end of the human C alpha 2 as well as in that of mouse and rat single C alpha genes. The 5682-bp sequence of clone lambda p18 described here starts 3' of C alpha 1 and presents three open reading frames; one of them contains part of the tandem repeats with the 20-bp consensus described previously that is expressed in a poly(A)(+) RNA and found in three dbEST clones of the human tonsillar cDNA library. Here, we demonstrate that in the CLF1 B lymphoblastoid cell line, this transcript is associated with polysomes. We also discuss the possibility of the presence of a new regulatory gene that does not encode an immunoglobulin and maps in the human IG heavy chain gene cluster. (C) 1998 Elsevier Science B.V. All rights reserved