Expression of the aminopeptidase N (CD13) gene in the human T cell lines HuT78 and H9.
The membrane-bound metalloprotease aminopeptidase N (APN, CD13, EC 3.4.11.2) is a well-established marker of normal and malignant cells of the myelomonocytic lineages. It is also expressed by leukemic blasts of a small group of patients suffering from acute or chronic lymphoid leukemia. CD13-specific monoclonal antibodies do not bind to the surface of normal B lymphocytes and APN-mRNA was not detectable by Northern analysis in normal lymphocytes or in T cell lines. A recent paper, however, describes the expression of CD13 on concanavalin A-stimulated T cells. Here, by means of enzymatic amplification of cDNA, cloning and sequencing of amplified cDNA fragments, in situ hybridization, and transcription start site mapping, evidence is provided that the human T cell lines HuT78 and H9 do contain APN-mRNA. Ala-pNA-hydrolyzing activity was detected in viable cells and cell homogenates as well as in size-fractionated protein fractions. Alanine-beta-naphthylamide (Ala-beta NA)-hydrolyzing activity was readily detectable after isoelectric focusing and blotting and was shown to be localized exclusively intracellularly in both cell lines. Usage of aminopeptidase-specific effectors revealed this activity to be distinct from CD13.
Lendeckel
U
U
Department of Internal Medicine, University of Magdeburg, Germany.
Wex
T
T
Kähne
T
T
Frank
K
K
Reinhold
D
D
Ansorge
S
S
D000626:Aminopeptidases / Q000378:metabolism*; D015703:Antigens, CD / Q000378:metabolism*; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism*; D001483:Base Sequence; D015153:Blotting, Western; D018826:CD13 Antigens; D002460:Cell Line; D017931:DNA Primers / Q000737:chemistry; D015870:Gene Expression; D006801:Humans; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D013601:T-Lymphocytes / Q000201:enzymology*; D014158:Transcription, Genetic
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D017931:DNA Primers; D012333:RNA, Messenger; D000626:Aminopeptidases; D018826:CD13 Antigens