Comparison of the primary structures of clathrin light chains from bovine brain and adrenal gland by peptide mapping.

Abstract

The structures of the polymorphic forms of clathrin light chains were analyzed by two peptide mapping procedures. Comparison of the products of partial digestion by V8 protease showed no common peptides between LCA and LCB from bovine brain. No similarities between clathrin light chains and tropomyosin chains from bovine brain and skeletal muscle were detected with this technique. The peptides produced by complete tryptic digestion of LCA and LCB from bovine brain and bovine adrenal gland were analyzed by reverse phase h.p.l.c. For both LCA and LCB the polypeptides from different tissues showed considerable homology. LCA from brain and adrenal gland shared 10 out of a total of 15 peptides. LCB from brain and adrenal gland shared 10 out of 14 peptides. In contrast, when LCA was compared with the LCB chain from the same tissue very few peptides were shared; 4/23 for brain and 3/21 for adrenal gland. These results strongly indicate that, within a tissue, LCB is not related to LCA by post‐translational processing and that each chain is encoded by a separate gene. The data also demonstrate the close homology of the different forms of LCA and LCB expressed in different tissues within the same organism. Thus the polymorphic differences of clathrin light chains within a tissue are greater than those between tissues.

Clathrin Light Chains LCA and LCB Are Similar, Polymorphic, and Share Repeated Heptad Motifs

“…Purified LCA and LCB wil compete with each other for the same binding site on the heavy chain (12). The peptide maps of LCA and LCB are different (11)(12)(13), however, and monoclonal antibodies to each of the light chains can distinguish chains of each class (6,14). Taken together, these observations suggest that LCA and LCB are related proteins that are encoded by different genes.…”

“…Light chains (LCA or LCB) from tissues other than brain are smaller than their brain counterparts by 2000 to 3000 daltons (10). Brain (11). Purified LCA and LCB wil compete with each other for the same binding site on the heavy chain (12).…”

“…The major species of bovine brain clathrin light chains LCA (-36 kD) and LCB (-33 kD) were isolated by preparative SDS (12 percent)-PAGE from a crude mixture of soluble light chains obtained from a boiled solution of clathrin trimers (11,15,16). The electroeluted light chains were succinylated and digested with trypsin, and several tryptic fragments were purified by reversedphase high-pressure liquid chromatography (17).…”

Purification of Golgi adaptor protein 1 from bovine adrenal gland and characterization of its β1 (β′) subunit by microsequencing

“…1). The heavy chain of adrenal gland clathrin eluted together with two-light chain isoforms of the non-neuronal type (Holmes et al, 1984). At this stage, clathrin (yield = 13 mg) was already 90% homogeneous, while the adaptors made up approximately 30% of the proteins in fractions 7-10 ( Fig.…”

Mapping two functional domains of clathrin light chains with monoclonal antibodies

“…Two forms of CAPs exist in cells of higher vertebrates: 33-kD (CAP2) and 36-kD (CAP1) forms are observed in tissues of neuronal origin, while analogous 28-and 30-kD forms are observed in other tissues (4). The two forms isolated from brain tissue have several features in common, including the ability to bind calmodulin (9) and a single site on the clathrin heavy chain (14), an essential role in mediating the action of an uncoating ATPase (11), and resistance to denaturation by heating (9), a property that facilitates their purification.…”