Evidence for Different Human Tracheobronchial Mucin Peptides Deduced from Nucleotide cDNA Sequences

Abstract

Highly glycosylated regions or glycopeptides were obtained by proteolysis of human tracheobronchial mucins. They were chemically deglycosylated and the resulting products were used to raise a rabbit antiserum. This antiserum specifically recognized the superanuclear region of respiratory and colonic goblet cells as areas around and below the nucleus of mucin-secreting cells in tracheobronchial mucous glands. A lambda gt11 cDNA library constructed from human tracheobronchial mucosa was screened with this antiserum. Ten positive clones were obtained from screening half of the library (about 10(6) recombinants). The antibodies were purified by absorption to each positive clone; some purified antibodies were specific for goblet cells and others recognized both goblet and mucous cells, indicating that there is differential cellular expression of mucin peptides. The total or partial amino acid sequences deduced from these cDNA clones could be classified into three groups. The first group contained repetitive sequences of eight amino acid residues, almost perfectly identical, and in different arrangements. The second type exhibited homology at their amino and carboxy-terminal ends. The last group had no distinctive feature except for a high content of hydroxy amino acids typical of mucins. Five different clones could correspond to the carboxy-terminal end of tracheobronchial apomucins. These results indicate that human tracheobronchial apomucins consist of a family of different proteins.

Cloning of the Amino-terminal and 5′-Flanking Region of the Human MUC5AC Mucin Gene and Transcriptional Up-regulation by Bacterial Exoproducts

“…The structure of the MUC5AC carboxyl terminus has been known since the cloning of NP3a, a cDNA isolated from a nasal polyp library. Its identification as part of MUC5AC rests on the fact that cDNAs containing part of the NP3a sequence had previously been designated as MUC5 (25) and were later designated as MUC5AC (19) The recognition that NP3a comprises the gene's 3Ј-end rests on its containing a polyadenylation signal and poly(A) tail. It also contains a homologue of the MUC2 D-domain 4 (8).…”

Molecular cloning of a major human gall bladder mucin: complete C-terminal sequence and genomic organization of MUC5B

“…At present, at least nine human mucin gene products have been identified and the complete nucleotide sequences of MUC1 [12][13][14][15], MUC2 [16][17][18][19] and MUC7 [20] have been reported. In addition, partial sequences of MUC3 [21], MUC4 [22], MUC5 (now referred to as MUC5AC ; [23][24][25][26][27]), MUC5B [28], MUC6 [29], a novel tracheobronchial mucin (possibly MUC8 ; [30]) and a sublingual-gland mucin [31] have been described. All of these proteins contain tandem repeating sequences, rich in serine, threonine and proline, Abbreviation used : pfu, plaque-forming units.…”

MUC4 mucin expression in human pancreatic tumours is affected by organ environment: the possible role of TGFβ2

“…They are produced mainly by the secretory epithelial cells for the lubrication and protection of ducts and lumen within the human body (Gendler and Spicer, 1995). In all, 14 human mucin genes have been identified, designated as MUC1-4, MUC5B, MUC5AC, MUC6-8, MUC11-12, MUC13, and MUC16-17 (Gendler et al, 1990;Lan et al, 1990;Aubert et al, 1991;Porchet et al, 1991;Bobek et al, 1993;Dufosse et al, 1993;Gum et al, 1994Gum et al, , 1997Shankar et al, 1997;Toribara et al, 1997;Williams et al, 1999Williams et al, , 2001Yin and Lloyd, 2001;Gum Jr et al, 2002). Based on the structure, mucins are categorised into three distinct forms: membrane spanning (MUC1, MUC3, MUC4, MUC12 and MUC17), gel forming (MUC2, MUC5AC, MUC5B and MUC6), and soluble (MUC7) .…”