Heterogeneous glycosylation of Musca domestica arylphorin

The Musca domestica larval hexamerin is composed of multiple, similar polypeptides

The Musca domestica larval hexamerin (MdHex-L) is a hexameric glycoprotein with an apparent native molecular weight of 500 kDa. Seven different cDNAs that encode MdHex-L subunits were cloned and sequenced. Furthermore, amino acid sequences of isolated subunits were determined by the Edman degradation method and compared to the conceptual translation products derived from the cloned cDNAs. The obtained data indicate the existence of multiple forms of MdHex-L subunits and that these multiple forms may be grouped into three categories according to their percentages of nucleotide sequence identity.

Expression patterns of the larval and adult hexamerin genes of Musca domestica

Hexamerins are proteins found in high abundance in the haemolymph of larval and adult insects. The expression patterns of the genes encoding the house fly, Musca domestica, hexamerins were determined by Northern analyses using cDNAs as probes. A cDNA, A1, hybridized to a fat body-specific messenger RNA (mRNA) which is detectable in larvae until pupation. Antibodies raised to the larval-specific hexamerin, Hex-L, bind recombinant protein encoded by a 5' rapid amplification of cDNA ends (RACE) product of A1, A2, indicating that the A cDNAs likely represent the genes encoding Hex-L. The F1, F2 and F3 cDNAs, corresponding to genes encoding an adult, female-enriched hexamerin, Hex-F, hybridized with an mRNA isolated from protein-fed females which has a temporal expression profile similar to that observed for the accumulation of Hex-F. Furthermore, expression of the mRNAs hybridizing to the F cDNAs is correlated with the abundance of Hex-F protein during the gonotrophic cycles. The mRNA transcription profiles indicate that the Hex-L and Hex-F genes are regulated in a sex-, tissue- and developmental phase-dependent manner. This stage-specific expression of hexamerins contrasts with the expression patterns of hexamerins seen in other insects. The conceptual translation products of larval hexamerin cDNAs showed identity with larval serum protein 1 (LSP1)-type hexamerins while the deduced products of the female hexamerin cDNAs showed the highest identity with LSP2-type hexamerins. Genomic analyses showed that the larval hexamerin and female hexamerin genes from M. domestica belong to two distinct multigenic families.

Complete cDNA and gene sequence of the developmentally regulated arylphorin of Calliphora vicina and its homology to insect hemolymph proteins and arthropod hemocyanins

Two cDNA libraries were prepared from poly(A)+ RNA isolated from fat bodies of last instar larvae of the blowfly Calliphora vicina. The libraries were probed with a genomic clone containing the coding sequence for an arylphorin subunit. Two cDNA clones as well as the genomic clone were mapped and their nucleotide sequences were determined. This revealed the presence of an open reading frame corresponding to a polypeptide with 759 amino acid residues. The deduced primary structure of Calliphora arylphorin and hemolymph proteins of other insect species and arthropod hemocyanine show nearly 30% identity. Highly conserved regions could be also identified.